diff --git a/harness/temporalHelpers.js b/harness/temporalHelpers.js
index 5a68db2343..e4425d6c5f 100644
--- a/harness/temporalHelpers.js
+++ b/harness/temporalHelpers.js
@@ -1589,63 +1589,6 @@ var TemporalHelpers = {
     });
   },
 
-  /*
-   * A custom calendar that does not allow any of its methods to be called, for
-   * the purpose of asserting that a particular operation does not call into
-   * user code.
-   */
-  calendarThrowEverything() {
-    class CalendarThrowEverything extends Temporal.Calendar {
-      constructor() {
-        super("iso8601");
-      }
-      toString() {
-        TemporalHelpers.assertUnreachable("toString should not be called");
-      }
-      dateFromFields() {
-        TemporalHelpers.assertUnreachable("dateFromFields should not be called");
-      }
-      yearMonthFromFields() {
-        TemporalHelpers.assertUnreachable("yearMonthFromFields should not be called");
-      }
-      monthDayFromFields() {
-        TemporalHelpers.assertUnreachable("monthDayFromFields should not be called");
-      }
-      dateAdd() {
-        TemporalHelpers.assertUnreachable("dateAdd should not be called");
-      }
-      dateUntil() {
-        TemporalHelpers.assertUnreachable("dateUntil should not be called");
-      }
-      era() {
-        TemporalHelpers.assertUnreachable("era should not be called");
-      }
-      eraYear() {
-        TemporalHelpers.assertUnreachable("eraYear should not be called");
-      }
-      year() {
-        TemporalHelpers.assertUnreachable("year should not be called");
-      }
-      month() {
-        TemporalHelpers.assertUnreachable("month should not be called");
-      }
-      monthCode() {
-        TemporalHelpers.assertUnreachable("monthCode should not be called");
-      }
-      day() {
-        TemporalHelpers.assertUnreachable("day should not be called");
-      }
-      fields() {
-        TemporalHelpers.assertUnreachable("fields should not be called");
-      }
-      mergeFields() {
-        TemporalHelpers.assertUnreachable("mergeFields should not be called");
-      }
-    }
-
-    return new CalendarThrowEverything();
-  },
-
   /*
    * oneShiftTimeZone(shiftInstant, shiftNanoseconds):
    *
@@ -1826,30 +1769,6 @@ var TemporalHelpers = {
     });
   },
 
-  /*
-   * A custom time zone that does not allow any of its methods to be called, for
-   * the purpose of asserting that a particular operation does not call into
-   * user code.
-   */
-  timeZoneThrowEverything() {
-    class TimeZoneThrowEverything extends Temporal.TimeZone {
-      constructor() {
-        super("UTC");
-      }
-      getOffsetNanosecondsFor() {
-        TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be called");
-      }
-      getPossibleInstantsFor() {
-        TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be called");
-      }
-      toString() {
-        TemporalHelpers.assertUnreachable("toString should not be called");
-      }
-    }
-
-    return new TimeZoneThrowEverything();
-  },
-
   /*
    * Returns an object that will append logs of any Gets or Calls of its valueOf
    * or toString properties to the array calls. Both valueOf and toString will
diff --git a/test/built-ins/Temporal/Duration/compare/instances-identical.js b/test/built-ins/Temporal/Duration/compare/instances-identical.js
index 70b6a068c6..5fb04708a0 100644
--- a/test/built-ins/Temporal/Duration/compare/instances-identical.js
+++ b/test/built-ins/Temporal/Duration/compare/instances-identical.js
@@ -3,10 +3,7 @@
 
 /*---
 esid: sec-temporal.duration.compare
-description: >
-  Shortcut return with no observable user code calls when two Temporal.Duration
-  have identical internal slots
-includes: [temporalHelpers.js]
+description: Return when two Temporal.Durations have identical internal slots
 features: [Temporal]
 ---*/
 
@@ -22,23 +19,9 @@ assert.sameValue(
   "relativeTo is not required if two distinct Duration instances are identical"
 );
 
-const calendar = TemporalHelpers.calendarThrowEverything();
-const relativeTo = new Temporal.PlainDate(2000, 1, 1, calendar);
-assert.sameValue(
-  Temporal.Duration.compare(dateDuration1, dateDuration2, { relativeTo }),
-  0,
-  "no calendar methods are called if two distinct Duration instances are identical"
-);
-
 const dateDuration3 = new Temporal.Duration(5, 5, 5, 5, 4, 65, 5, 5, 5, 5);
 assert.throws(
   RangeError,
   () => Temporal.Duration.compare(dateDuration1, dateDuration3),
   "relativeTo is required if two Duration instances are the same length but not identical"
 );
-
-assert.throws(
-  Test262Error,
-  () => Temporal.Duration.compare(dateDuration1, dateDuration3, { relativeTo }),
-  "calendar methods are called if two Duration instances are the same length but not identical"
-);
diff --git a/test/built-ins/Temporal/Duration/compare/relativeto-propertybag-timezone-string.js b/test/built-ins/Temporal/Duration/compare/relativeto-propertybag-timezone-string.js
index 99bd588523..d1c71a5f9b 100644
--- a/test/built-ins/Temporal/Duration/compare/relativeto-propertybag-timezone-string.js
+++ b/test/built-ins/Temporal/Duration/compare/relativeto-propertybag-timezone-string.js
@@ -4,32 +4,11 @@
 /*---
 esid: sec-temporal.duration.compare
 description: Time zone IDs are valid input for a time zone
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 // The following are all valid strings so should not throw:
 
 ["UTC", "+01:00"].forEach((timeZone) => {
   Temporal.Duration.compare(new Temporal.Duration(1), new Temporal.Duration(), { relativeTo: { year: 2000, month: 5, day: 2, timeZone } });
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/Duration/prototype/round/relativeto-propertybag-timezone-string.js b/test/built-ins/Temporal/Duration/prototype/round/relativeto-propertybag-timezone-string.js
index 2061506da3..a279c3cdea 100644
--- a/test/built-ins/Temporal/Duration/prototype/round/relativeto-propertybag-timezone-string.js
+++ b/test/built-ins/Temporal/Duration/prototype/round/relativeto-propertybag-timezone-string.js
@@ -4,27 +4,9 @@
 /*---
 esid: sec-temporal.duration.prototype.round
 description: Time zone IDs are valid input for a time zone
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 const instance = new Temporal.Duration(1);
 
 // The following are all valid strings so should not throw:
@@ -32,6 +14,3 @@ const instance = new Temporal.Duration(1);
 ["UTC", "+01:00"].forEach((timeZone) => {
   instance.round({ largestUnit: "months", relativeTo: { year: 2000, month: 5, day: 2, timeZone } });
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/Duration/prototype/round/rounding-is-noop.js b/test/built-ins/Temporal/Duration/prototype/round/rounding-is-noop.js
index a87149badb..94591004dd 100644
--- a/test/built-ins/Temporal/Duration/prototype/round/rounding-is-noop.js
+++ b/test/built-ins/Temporal/Duration/prototype/round/rounding-is-noop.js
@@ -4,16 +4,13 @@
 /*---
 esid: sec-temporal.duration.prototype.round
 description: >
-  No calendar or time zone methods are called under circumstances where rounding
-  is a no-op
+  Circumstances where rounding is a no-op, return a new but equal duration
 includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const calendar = TemporalHelpers.calendarThrowEverything();
-const timeZone = TemporalHelpers.timeZoneThrowEverything();
-const plainRelativeTo = new Temporal.PlainDate(2000, 1, 1, calendar);
-const zonedRelativeTo = new Temporal.ZonedDateTime(0n, timeZone, calendar);
+const plainRelativeTo = new Temporal.PlainDate(2000, 1, 1, "iso8601");
+const zonedRelativeTo = new Temporal.ZonedDateTime(0n, "UTC", "iso8601");
 
 const d = new Temporal.Duration(0, 0, 0, 0, 23, 59, 59, 999, 999, 997);
 
@@ -38,49 +35,3 @@ for (const [duration, options, descr] of noopRoundingOperations) {
   assert.notSameValue(negResult, negDuration, "rounding result should be a new object (negative)");
   TemporalHelpers.assertDurationsEqual(negResult, negDuration, `rounding should be a no-op with ${descr} (negative)`);
 }
-
-// These operations are not no-op rounding operations, but still should not call
-// any calendar methods:
-const roundingOperationsNotCallingCalendarMethods = [
-  [d, { smallestUnit: "microseconds" }, "round to 1 µs"],
-  [d, { smallestUnit: "nanoseconds", roundingIncrement: 2 }, "round to 2 ns"],
-  [new Temporal.Duration(0, 0, 0, 0, 24), { largestUnit: "days" }, "upwards balancing requested"],
-  [d, { largestUnit: "minutes" }, "downwards balancing requested"],
-  [new Temporal.Duration(0, 0, 0, 0, 1, 120), { smallestUnit: "nanoseconds" }, "time units could overflow"],
-  [new Temporal.Duration(0, 0, 0, 1, 24), { smallestUnit: "nanoseconds" }, "hours-to-days conversion could occur"],
-];
-for (const [duration, options, descr] of roundingOperationsNotCallingCalendarMethods) {
-  const result = duration.round(options);
-  let equal = true;
-  for (const prop of ['years', 'months', 'weeks', 'days', 'hours', 'minutes', 'seconds', 'milliseconds', 'microseconds', 'nanoseconds']) {
-    if (result[prop] !== duration[prop]) {
-      equal = false;
-      break;
-    }
-  }
-  assert(!equal, `round result ${result} should be different from ${duration} with ${descr}`);
-
-  const negDuration = duration.negated();
-  const negResult = negDuration.round(options);
-  equal = true;
-  for (const prop of ['years', 'months', 'weeks', 'days', 'hours', 'minutes', 'seconds', 'milliseconds', 'microseconds', 'nanoseconds']) {
-    if (negResult[prop] !== negDuration[prop]) {
-      equal = false;
-      break;
-    }
-  }
-  assert(!equal, `round result ${negResult} should be different from ${negDuration} with ${descr} (negative)`);
-}
-
-// These operations should not be short-circuited because they have to call
-// calendar methods:
-const roundingOperationsCallingCalendarMethods = [
-  [new Temporal.Duration(0, 0, 1), { smallestUnit: "nanoseconds", relativeTo: plainRelativeTo }, "calendar units present"],
-  [d, { largestUnit: "days", relativeTo: zonedRelativeTo }, "largestUnit days with zoned relativeTo"],
-  [new Temporal.Duration(0, 0, 0, 1), { smallestUnit: "nanoseconds", relativeTo: zonedRelativeTo }, "hours-to-days conversion could occur with zoned relativeTo"],
-];
-
-for (const [duration, options, descr] of roundingOperationsCallingCalendarMethods) {
-  assert.throws(Test262Error, () => duration.round(options), `rounding should not be a no-op with ${descr}`);
-  assert.throws(Test262Error, () => duration.negated().round(options), `rounding should not be a no-op with ${descr} (negative)`);
-}
diff --git a/test/built-ins/Temporal/Duration/prototype/total/relativeto-propertybag-timezone-string.js b/test/built-ins/Temporal/Duration/prototype/total/relativeto-propertybag-timezone-string.js
index 4bd5209ab9..9269225e56 100644
--- a/test/built-ins/Temporal/Duration/prototype/total/relativeto-propertybag-timezone-string.js
+++ b/test/built-ins/Temporal/Duration/prototype/total/relativeto-propertybag-timezone-string.js
@@ -4,27 +4,9 @@
 /*---
 esid: sec-temporal.duration.prototype.total
 description: Time zone IDs are valid input for a time zone
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 const instance = new Temporal.Duration(1);
 
 // The following are all valid strings so should not throw:
@@ -32,6 +14,3 @@ const instance = new Temporal.Duration(1);
 ["UTC", "+01:00"].forEach((timeZone) => {
   instance.total({ unit: "months", relativeTo: { year: 2000, month: 5, day: 2, timeZone } });
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/Instant/from/timezone-custom.js b/test/built-ins/Temporal/Instant/from/timezone-custom.js
index 6063d6f5c8..51dcadaf79 100644
--- a/test/built-ins/Temporal/Instant/from/timezone-custom.js
+++ b/test/built-ins/Temporal/Instant/from/timezone-custom.js
@@ -7,13 +7,5 @@ description: Time zone annotation is ignored in input ISO string
 features: [Temporal]
 ---*/
 
-const dateTimeString = "1975-02-02T14:25:36.123456789";
-
-Object.defineProperty(Temporal.TimeZone, "from", {
-  get() {
-    throw new Test262Error("should not get Temporal.TimeZone.from");
-  },
-});
-
-const instant = Temporal.Instant.from(dateTimeString + "+01:00[Custom/TimeZone]");
+const instant = Temporal.Instant.from("1975-02-02T14:25:36.123456789+01:00[Invalid/TimeZone]");
 assert.sameValue(instant.epochMilliseconds, 160579536123);
diff --git a/test/built-ins/Temporal/Instant/prototype/toString/options-undefined.js b/test/built-ins/Temporal/Instant/prototype/toString/options-undefined.js
index 08dcbab63c..9e225f32cb 100644
--- a/test/built-ins/Temporal/Instant/prototype/toString/options-undefined.js
+++ b/test/built-ins/Temporal/Instant/prototype/toString/options-undefined.js
@@ -3,36 +3,20 @@
 
 /*---
 esid: sec-temporal.instant.prototype.tostring
-includes: [compareArray.js]
 description: Verify that undefined options are handled correctly.
 features: [Temporal]
 ---*/
 
-const actual = [];
-const expected = [];
-
 const instant = Temporal.Instant.from("1975-02-02T14:25:36.12345Z");
 
-Object.defineProperty(Temporal.TimeZone, "from", {
-  get() {
-    actual.push("get Temporal.TimeZone.from");
-    return function(identifier) {
-      actual.push("call Temporal.TimeZone.from");
-      assert.sameValue(identifier, "UTC");
-    };
-  },
-});
-
 assert.sameValue(
   instant.toString(),
   "1975-02-02T14:25:36.12345Z",
   "default time zone is none, precision is auto, and rounding is trunc"
 );
-assert.compareArray(actual, expected);
 
 assert.sameValue(
   instant.toString(undefined),
   "1975-02-02T14:25:36.12345Z",
   "default time zone is none, precision is auto, and rounding is trunc"
 );
-assert.compareArray(actual, expected);
diff --git a/test/built-ins/Temporal/Instant/prototype/toString/timezone-string.js b/test/built-ins/Temporal/Instant/prototype/toString/timezone-string.js
index 9c6346a65c..9c7ba8d863 100644
--- a/test/built-ins/Temporal/Instant/prototype/toString/timezone-string.js
+++ b/test/built-ins/Temporal/Instant/prototype/toString/timezone-string.js
@@ -4,27 +4,9 @@
 /*---
 esid: sec-temporal.instant.prototype.tostring
 description: Time zone IDs are valid input for a time zone
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 const instance = new Temporal.Instant(0n);
 
 const result1 = instance.toString({ timeZone: "UTC" });
@@ -32,6 +14,3 @@ assert.sameValue(result1.substr(-6), "+00:00", "Time zone created from string 'U
 
 const result2 = instance.toString({ timeZone: "-01:30" });
 assert.sameValue(result2.substr(-6), "-01:30", "Time zone created from string '-01:30'");
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/Instant/prototype/toZonedDateTimeISO/timezone-string.js b/test/built-ins/Temporal/Instant/prototype/toZonedDateTimeISO/timezone-string.js
index 1c4d9b66c8..236cb0688d 100644
--- a/test/built-ins/Temporal/Instant/prototype/toZonedDateTimeISO/timezone-string.js
+++ b/test/built-ins/Temporal/Instant/prototype/toZonedDateTimeISO/timezone-string.js
@@ -8,29 +8,9 @@ includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 const instance = new Temporal.Instant(0n);
 
 ["UTC", "+01:30"].forEach((timeZone) => {
   const result = instance.toZonedDateTimeISO(timeZone);
   assert.sameValue(result.getISOFields().timeZone, timeZone, `time zone slot should store string "${timeZone}"`);
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/Now/plainDateISO/timezone-string.js b/test/built-ins/Temporal/Now/plainDateISO/timezone-string.js
index 0062a04bac..d9a452e2df 100644
--- a/test/built-ins/Temporal/Now/plainDateISO/timezone-string.js
+++ b/test/built-ins/Temporal/Now/plainDateISO/timezone-string.js
@@ -4,32 +4,11 @@
 /*---
 esid: sec-temporal.now.plaindateiso
 description: Time zone IDs are valid input for a time zone
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 // The following are all valid strings so should not throw:
 
 ["UTC", "+01:00"].forEach((timeZone) => {
   Temporal.Now.plainDateISO(timeZone);
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/Now/plainDateTimeISO/time-zone-undefined.js b/test/built-ins/Temporal/Now/plainDateTimeISO/time-zone-undefined.js
index 6d719c2e91..518a306eff 100644
--- a/test/built-ins/Temporal/Now/plainDateTimeISO/time-zone-undefined.js
+++ b/test/built-ins/Temporal/Now/plainDateTimeISO/time-zone-undefined.js
@@ -4,32 +4,17 @@
 /*---
 esid: sec-temporal.now.plaindatetimeiso
 description: Functions when time zone argument is omitted
-includes: [compareArray.js]
 features: [Temporal]
 ---*/
 
-const actual = [];
-const expected = [];
-
-Object.defineProperty(Temporal.TimeZone, "from", {
-  get() {
-    actual.push("get Temporal.TimeZone.from");
-    return undefined;
-  },
-});
-
 const resultExplicit = Temporal.Now.plainDateTimeISO(undefined);
 assert(
   resultExplicit instanceof Temporal.PlainDateTime,
   'The result of evaluating (resultExplicit instanceof Temporal.PlainDateTime) is expected to be true'
 );
 
-assert.compareArray(actual, expected, 'The value of actual is expected to equal the value of expected');
-
 const resultImplicit = Temporal.Now.plainDateTimeISO();
 assert(
   resultImplicit instanceof Temporal.PlainDateTime,
   'The result of evaluating (resultImplicit instanceof Temporal.PlainDateTime) is expected to be true'
 );
-
-assert.compareArray(actual, expected, 'The value of actual is expected to equal the value of expected');
diff --git a/test/built-ins/Temporal/Now/plainDateTimeISO/timezone-string.js b/test/built-ins/Temporal/Now/plainDateTimeISO/timezone-string.js
index 2cdab47af0..a4aebae5a5 100644
--- a/test/built-ins/Temporal/Now/plainDateTimeISO/timezone-string.js
+++ b/test/built-ins/Temporal/Now/plainDateTimeISO/timezone-string.js
@@ -4,32 +4,11 @@
 /*---
 esid: sec-temporal.now.plaindatetimeiso
 description: Time zone IDs are valid input for a time zone
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 // The following are all valid strings so should not throw:
 
 ["UTC", "+01:00"].forEach((timeZone) => {
   Temporal.Now.plainDateTimeISO(timeZone);
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/Now/plainTimeISO/timezone-string.js b/test/built-ins/Temporal/Now/plainTimeISO/timezone-string.js
index a8fa8c3713..939f6afa0a 100644
--- a/test/built-ins/Temporal/Now/plainTimeISO/timezone-string.js
+++ b/test/built-ins/Temporal/Now/plainTimeISO/timezone-string.js
@@ -4,32 +4,11 @@
 /*---
 esid: sec-temporal.now.plaintimeiso
 description: Time zone IDs are valid input for a time zone
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 // The following are all valid strings so should not throw:
 
 ["UTC", "+01:00"].forEach((timeZone) => {
   Temporal.Now.plainTimeISO(timeZone);
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/Now/zonedDateTimeISO/time-zone-undefined.js b/test/built-ins/Temporal/Now/zonedDateTimeISO/time-zone-undefined.js
index ed290b5c0c..e0b6bae3e0 100644
--- a/test/built-ins/Temporal/Now/zonedDateTimeISO/time-zone-undefined.js
+++ b/test/built-ins/Temporal/Now/zonedDateTimeISO/time-zone-undefined.js
@@ -8,24 +8,10 @@ includes: [compareArray.js]
 features: [Temporal]
 ---*/
 
-const actual = [];
-const expected = [];
-
-Object.defineProperty(Temporal.TimeZone, "from", {
-  get() {
-    actual.push("get Temporal.TimeZone.from");
-    return undefined;
-  },
-});
-
 const systemTimeZone = Temporal.Now.timeZoneId();
 
 const resultExplicit = Temporal.Now.zonedDateTimeISO(undefined);
 assert.sameValue(resultExplicit.getISOFields().timeZone, systemTimeZone, "time zone slot should store a string");
 
-assert.compareArray(actual, expected, "Temporal.TimeZone.from should not be called");
-
 const resultImplicit = Temporal.Now.zonedDateTimeISO();
 assert.sameValue(resultImplicit.getISOFields().timeZone, systemTimeZone, "time zone slot should store a string");
-
-assert.compareArray(actual, expected, "Temporal.TimeZone.from should not be called");
diff --git a/test/built-ins/Temporal/Now/zonedDateTimeISO/timezone-string.js b/test/built-ins/Temporal/Now/zonedDateTimeISO/timezone-string.js
index 9ec4d1b278..9a27fad073 100644
--- a/test/built-ins/Temporal/Now/zonedDateTimeISO/timezone-string.js
+++ b/test/built-ins/Temporal/Now/zonedDateTimeISO/timezone-string.js
@@ -8,27 +8,7 @@ includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 ["UTC", "+01:30"].forEach((timeZone) => {
   const result = Temporal.Now.zonedDateTimeISO(timeZone);
   assert.sameValue(result.getISOFields().timeZone, timeZone, `Time zone created from string "${timeZone}"`);
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/PlainDate/basic.js b/test/built-ins/Temporal/PlainDate/basic.js
index ade4653c7b..a01a726e9c 100644
--- a/test/built-ins/Temporal/PlainDate/basic.js
+++ b/test/built-ins/Temporal/PlainDate/basic.js
@@ -8,17 +8,6 @@ includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-Object.defineProperty(Temporal.Calendar, "from", {
-  get() {
-    throw new Test262Error("Should not get Calendar.from");
-  },
-});
-
-const calendar = new Temporal.Calendar("iso8601");
-const plainDateWithObject = new Temporal.PlainDate(2020, 12, 24, calendar);
-TemporalHelpers.assertPlainDate(plainDateWithObject, 2020, 12, "M12", 24, "with object");
-assert.sameValue(plainDateWithObject.getISOFields().calendar, calendar);
-
-const plainDateWithString = new Temporal.PlainDate(2020, 12, 24, "iso8601");
-TemporalHelpers.assertPlainDate(plainDateWithString, 2020, 12, "M12", 24, "with string");
-assert.sameValue(plainDateWithString.getISOFields().calendar, "iso8601", "calendar slot should store a string");
+const plainDate = new Temporal.PlainDate(2020, 12, 24, "iso8601");
+TemporalHelpers.assertPlainDate(plainDate, 2020, 12, "M12", 24, "with string");
+assert.sameValue(plainDate.getISOFields().calendar, "iso8601", "calendar slot should store a string");
diff --git a/test/built-ins/Temporal/PlainDate/calendar-undefined.js b/test/built-ins/Temporal/PlainDate/calendar-undefined.js
index bd0f7e5dd6..68d2fe8251 100644
--- a/test/built-ins/Temporal/PlainDate/calendar-undefined.js
+++ b/test/built-ins/Temporal/PlainDate/calendar-undefined.js
@@ -9,12 +9,6 @@ features: [Temporal]
 
 const args = [2020, 12, 24];
 
-Object.defineProperty(Temporal.Calendar, "from", {
-  get() {
-    throw new Test262Error("Should not get Calendar.from");
-  },
-});
-
 const dateExplicit = new Temporal.PlainDate(...args, undefined);
 assert.sameValue(dateExplicit.getISOFields().calendar, "iso8601", "calendar slot should store string");
 
diff --git a/test/built-ins/Temporal/PlainDate/compare/argument-propertybag-calendar-string.js b/test/built-ins/Temporal/PlainDate/compare/argument-propertybag-calendar-string.js
index 0556a490be..c400baee24 100644
--- a/test/built-ins/Temporal/PlainDate/compare/argument-propertybag-calendar-string.js
+++ b/test/built-ins/Temporal/PlainDate/compare/argument-propertybag-calendar-string.js
@@ -4,19 +4,9 @@
 /*---
 esid: sec-temporal.plaindate.compare
 description: A calendar ID is valid input for Calendar
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const dateFromFieldsOriginal = Object.getOwnPropertyDescriptor(Temporal.Calendar.prototype, "dateFromFields");
-Object.defineProperty(Temporal.Calendar.prototype, "dateFromFields", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("dateFromFields should not be looked up");
-  },
-});
-
 const calendar = "iso8601";
 
 const arg = { year: 1976, monthCode: "M11", day: 18, calendar };
@@ -26,5 +16,3 @@ assert.sameValue(result1, 0, `Calendar created from string "${arg}" (first argum
 
 const result2 = Temporal.PlainDate.compare(new Temporal.PlainDate(1976, 11, 18), arg);
 assert.sameValue(result2, 0, `Calendar created from string "${arg}" (second argument)`);
-
-Object.defineProperty(Temporal.Calendar.prototype, "dateFromFields", dateFromFieldsOriginal);
diff --git a/test/built-ins/Temporal/PlainDate/prototype/toZonedDateTime/timezone-string.js b/test/built-ins/Temporal/PlainDate/prototype/toZonedDateTime/timezone-string.js
index 6e4036ef43..dc93a41d33 100644
--- a/test/built-ins/Temporal/PlainDate/prototype/toZonedDateTime/timezone-string.js
+++ b/test/built-ins/Temporal/PlainDate/prototype/toZonedDateTime/timezone-string.js
@@ -8,29 +8,9 @@ includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 const instance = new Temporal.PlainDate(2000, 5, 2);
 
 ["UTC", "+01:30"].forEach((timeZone) => {
   const result = instance.toZonedDateTime(timeZone);
   assert.sameValue(result.getISOFields().timeZone, timeZone, `time zone slot should store string "${timeZone}"`);
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/PlainDateTime/calendar-undefined.js b/test/built-ins/Temporal/PlainDateTime/calendar-undefined.js
index e4a692d263..2654cb8e88 100644
--- a/test/built-ins/Temporal/PlainDateTime/calendar-undefined.js
+++ b/test/built-ins/Temporal/PlainDateTime/calendar-undefined.js
@@ -9,12 +9,6 @@ features: [Temporal]
 
 const dateTimeArgs = [2020, 12, 24, 12, 34, 56, 123, 456, 789];
 
-Object.defineProperty(Temporal.Calendar, "from", {
-  get() {
-    throw new Test262Error("Should not get Calendar.from");
-  },
-});
-
 const dateTimeExplicit = new Temporal.PlainDateTime(...dateTimeArgs, undefined);
 assert.sameValue(dateTimeExplicit.calendarId, "iso8601");
 
diff --git a/test/built-ins/Temporal/PlainDateTime/compare/argument-propertybag-calendar-string.js b/test/built-ins/Temporal/PlainDateTime/compare/argument-propertybag-calendar-string.js
index c5b7858472..4fada99c0b 100644
--- a/test/built-ins/Temporal/PlainDateTime/compare/argument-propertybag-calendar-string.js
+++ b/test/built-ins/Temporal/PlainDateTime/compare/argument-propertybag-calendar-string.js
@@ -4,19 +4,9 @@
 /*---
 esid: sec-temporal.plaindatetime.compare
 description: A calendar ID is valid input for Calendar
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const dateFromFieldsOriginal = Object.getOwnPropertyDescriptor(Temporal.Calendar.prototype, "dateFromFields");
-Object.defineProperty(Temporal.Calendar.prototype, "dateFromFields", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("dateFromFields should not be looked up");
-  },
-});
-
 const calendar = "iso8601";
 
 const arg = { year: 1976, monthCode: "M11", day: 18, calendar };
@@ -26,5 +16,3 @@ assert.sameValue(result1, 0, `Calendar created from string "${arg}" (first argum
 
 const result2 = Temporal.PlainDateTime.compare(new Temporal.PlainDateTime(1976, 11, 18), arg);
 assert.sameValue(result2, 0, `Calendar created from string "${arg}" (second argument)`);
-
-Object.defineProperty(Temporal.Calendar.prototype, "dateFromFields", dateFromFieldsOriginal);
diff --git a/test/built-ins/Temporal/PlainDateTime/compare/calendar-ignored.js b/test/built-ins/Temporal/PlainDateTime/compare/calendar-ignored.js
index 42b53741fa..f14fd2023f 100644
--- a/test/built-ins/Temporal/PlainDateTime/compare/calendar-ignored.js
+++ b/test/built-ins/Temporal/PlainDateTime/compare/calendar-ignored.js
@@ -8,12 +8,10 @@ includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const calendar1 = TemporalHelpers.calendarThrowEverything();
-const calendar2 = TemporalHelpers.calendarThrowEverything();
-const dt1 = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, calendar1);
-const dt2 = new Temporal.PlainDateTime(2019, 10, 29, 10, 46, 38, 271, 986, 102, calendar1);
-const dt3 = new Temporal.PlainDateTime(2019, 10, 29, 10, 46, 38, 271, 986, 102, calendar1);
-const dt4 = new Temporal.PlainDateTime(2019, 10, 29, 10, 46, 38, 271, 986, 102, calendar2);
+const dt1 = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, "iso8601");
+const dt2 = new Temporal.PlainDateTime(2019, 10, 29, 10, 46, 38, 271, 986, 102, "iso8601");
+const dt3 = new Temporal.PlainDateTime(2019, 10, 29, 10, 46, 38, 271, 986, 102, "iso8601");
+const dt4 = new Temporal.PlainDateTime(2019, 10, 29, 10, 46, 38, 271, 986, 102, "gregory");
 
 assert.sameValue(Temporal.PlainDateTime.compare(dt1, dt2), -1, "smaller");
 assert.sameValue(Temporal.PlainDateTime.compare(dt2, dt3), 0, "equal with same calendar");
diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/toZonedDateTime/timezone-string.js b/test/built-ins/Temporal/PlainDateTime/prototype/toZonedDateTime/timezone-string.js
index c685234e9c..0d4fb9e4d8 100644
--- a/test/built-ins/Temporal/PlainDateTime/prototype/toZonedDateTime/timezone-string.js
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/toZonedDateTime/timezone-string.js
@@ -8,29 +8,9 @@ includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 const instance = new Temporal.PlainDateTime(2000, 5, 2);
 
 ["UTC", "+01:30"].forEach((timeZone) => {
   const result = instance.toZonedDateTime(timeZone);
   assert.sameValue(result.getISOFields().timeZone, timeZone, `time zone slot should store string "${timeZone}"`);
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/PlainMonthDay/calendar-undefined.js b/test/built-ins/Temporal/PlainMonthDay/calendar-undefined.js
index 442da5e735..e779063228 100644
--- a/test/built-ins/Temporal/PlainMonthDay/calendar-undefined.js
+++ b/test/built-ins/Temporal/PlainMonthDay/calendar-undefined.js
@@ -9,12 +9,6 @@ features: [Temporal]
 
 const args = [5, 2];
 
-Object.defineProperty(Temporal.Calendar, "from", {
-  get() {
-    throw new Test262Error("Should not get Calendar.from");
-  },
-});
-
 const dateExplicit = new Temporal.PlainMonthDay(...args, undefined);
 assert.sameValue(dateExplicit.calendarId, "iso8601");
 
diff --git a/test/built-ins/Temporal/PlainMonthDay/prototype/toPlainDate/argument-not-object.js b/test/built-ins/Temporal/PlainMonthDay/prototype/toPlainDate/argument-not-object.js
index a64f4d2fbb..0d3105b561 100644
--- a/test/built-ins/Temporal/PlainMonthDay/prototype/toPlainDate/argument-not-object.js
+++ b/test/built-ins/Temporal/PlainMonthDay/prototype/toPlainDate/argument-not-object.js
@@ -3,13 +3,11 @@
 
 /*---
 esid: sec-temporal.plainmonthday.prototype.toplaindate
-description: Throws a TypeError if the argument is not an Object, before any other observable actions
-includes: [compareArray.js, temporalHelpers.js]
+description: Throws a TypeError if the argument is not an Object
 features: [BigInt, Symbol, Temporal]
 ---*/
 
 [null, undefined, true, 3.1416, "a string", Symbol("symbol"), 7n].forEach((primitive) => {
-  const calendar = TemporalHelpers.calendarThrowEverything();
-  const plainMonthDay = new Temporal.PlainMonthDay(5, 2, calendar);
+  const plainMonthDay = new Temporal.PlainMonthDay(5, 2);
   assert.throws(TypeError, () => plainMonthDay.toPlainDate(primitive));
 });
diff --git a/test/built-ins/Temporal/PlainYearMonth/calendar-undefined.js b/test/built-ins/Temporal/PlainYearMonth/calendar-undefined.js
index d08947cec8..24c5832acf 100644
--- a/test/built-ins/Temporal/PlainYearMonth/calendar-undefined.js
+++ b/test/built-ins/Temporal/PlainYearMonth/calendar-undefined.js
@@ -9,12 +9,6 @@ features: [Temporal]
 
 const args = [2000, 5];
 
-Object.defineProperty(Temporal.Calendar, "from", {
-  get() {
-    throw new Test262Error("Should not get Calendar.from");
-  },
-});
-
 const dateExplicit = new Temporal.PlainYearMonth(...args, undefined);
 assert.sameValue(dateExplicit.calendarId, "iso8601");
 
diff --git a/test/built-ins/Temporal/PlainYearMonth/compare/argument-propertybag-calendar-string.js b/test/built-ins/Temporal/PlainYearMonth/compare/argument-propertybag-calendar-string.js
index cabd399548..c6c04f6c6e 100644
--- a/test/built-ins/Temporal/PlainYearMonth/compare/argument-propertybag-calendar-string.js
+++ b/test/built-ins/Temporal/PlainYearMonth/compare/argument-propertybag-calendar-string.js
@@ -4,19 +4,9 @@
 /*---
 esid: sec-temporal.plainyearmonth.compare
 description: A calendar ID is valid input for Calendar
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const dateFromFieldsOriginal = Object.getOwnPropertyDescriptor(Temporal.Calendar.prototype, "dateFromFields");
-Object.defineProperty(Temporal.Calendar.prototype, "dateFromFields", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("dateFromFields should not be looked up");
-  },
-});
-
 const calendar = "iso8601";
 
 const arg = { year: 2019, monthCode: "M06", calendar };
@@ -26,5 +16,3 @@ assert.sameValue(result1, 0, `Calendar created from string "${arg}" (first argum
 
 const result2 = Temporal.PlainYearMonth.compare(new Temporal.PlainYearMonth(2019, 6), arg);
 assert.sameValue(result2, 0, `Calendar created from string "${arg}" (second argument)`);
-
-Object.defineProperty(Temporal.Calendar.prototype, "dateFromFields", dateFromFieldsOriginal);
diff --git a/test/built-ins/Temporal/PlainYearMonth/prototype/toPlainDate/argument-not-object.js b/test/built-ins/Temporal/PlainYearMonth/prototype/toPlainDate/argument-not-object.js
index 16c1e06340..eb3860c8b7 100644
--- a/test/built-ins/Temporal/PlainYearMonth/prototype/toPlainDate/argument-not-object.js
+++ b/test/built-ins/Temporal/PlainYearMonth/prototype/toPlainDate/argument-not-object.js
@@ -3,13 +3,11 @@
 
 /*---
 esid: sec-temporal.plainyearmonth.prototype.toplaindate
-description: Throws a TypeError if the argument is not an Object, before any other observable actions
-includes: [compareArray.js, temporalHelpers.js]
+description: Throws a TypeError if the argument is not an Object
 features: [BigInt, Symbol, Temporal]
 ---*/
 
 [null, undefined, true, 3.1416, "a string", Symbol("symbol"), 7n].forEach((primitive) => {
-  const calendar = TemporalHelpers.calendarThrowEverything();
-  const plainYearMonth = new Temporal.PlainYearMonth(2000, 5, calendar);
+  const plainYearMonth = new Temporal.PlainYearMonth(2000, 5);
   assert.throws(TypeError, () => plainYearMonth.toPlainDate(primitive));
 });
diff --git a/test/built-ins/Temporal/ZonedDateTime/calendar-undefined.js b/test/built-ins/Temporal/ZonedDateTime/calendar-undefined.js
index 6851efd813..3e8b1f446c 100644
--- a/test/built-ins/Temporal/ZonedDateTime/calendar-undefined.js
+++ b/test/built-ins/Temporal/ZonedDateTime/calendar-undefined.js
@@ -7,12 +7,6 @@ description: Calendar argument defaults to the built-in ISO 8601 calendar
 features: [BigInt, Temporal]
 ---*/
 
-
-Object.defineProperty(Temporal.Calendar, "from", {
-  get() {
-    throw new Test262Error("Should not get Calendar.from");
-  },
-});
 const args = [957270896987654321n, "UTC"];
 
 const explicit = new Temporal.ZonedDateTime(...args, undefined);
diff --git a/test/built-ins/Temporal/ZonedDateTime/compare/argument-propertybag-calendar-string.js b/test/built-ins/Temporal/ZonedDateTime/compare/argument-propertybag-calendar-string.js
index 7918945d00..acd56452b8 100644
--- a/test/built-ins/Temporal/ZonedDateTime/compare/argument-propertybag-calendar-string.js
+++ b/test/built-ins/Temporal/ZonedDateTime/compare/argument-propertybag-calendar-string.js
@@ -4,19 +4,9 @@
 /*---
 esid: sec-temporal.zoneddatetime.compare
 description: A calendar ID is valid input for Calendar
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const dateFromFieldsOriginal = Object.getOwnPropertyDescriptor(Temporal.Calendar.prototype, "dateFromFields");
-Object.defineProperty(Temporal.Calendar.prototype, "dateFromFields", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("dateFromFields should not be looked up");
-  },
-});
-
 const calendar = "iso8601";
 
 const timeZone = "UTC";
@@ -28,5 +18,3 @@ assert.sameValue(result1, 0, `Calendar created from string "${arg}" (first argum
 
 const result2 = Temporal.ZonedDateTime.compare(datetime, arg);
 assert.sameValue(result2, 0, `Calendar created from string "${arg}" (second argument)`);
-
-Object.defineProperty(Temporal.Calendar.prototype, "dateFromFields", dateFromFieldsOriginal);
diff --git a/test/built-ins/Temporal/ZonedDateTime/compare/argument-propertybag-timezone-string.js b/test/built-ins/Temporal/ZonedDateTime/compare/argument-propertybag-timezone-string.js
index 60b84e507c..3d56a08a53 100644
--- a/test/built-ins/Temporal/ZonedDateTime/compare/argument-propertybag-timezone-string.js
+++ b/test/built-ins/Temporal/ZonedDateTime/compare/argument-propertybag-timezone-string.js
@@ -4,27 +4,9 @@
 /*---
 esid: sec-temporal.zoneddatetime.compare
 description: Time zone IDs are valid input for a time zone
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 ["UTC", "+01:30"].forEach((timeZone) => {
   const epoch = new Temporal.ZonedDateTime(0n, timeZone);
 
@@ -32,6 +14,3 @@ Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
   Temporal.ZonedDateTime.compare({ year: 2020, month: 5, day: 2, timeZone }, epoch);
   Temporal.ZonedDateTime.compare(epoch, { year: 2020, month: 5, day: 2, timeZone });
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/ZonedDateTime/from/argument-propertybag-timezone-string.js b/test/built-ins/Temporal/ZonedDateTime/from/argument-propertybag-timezone-string.js
index a0a4175926..264fcbb478 100644
--- a/test/built-ins/Temporal/ZonedDateTime/from/argument-propertybag-timezone-string.js
+++ b/test/built-ins/Temporal/ZonedDateTime/from/argument-propertybag-timezone-string.js
@@ -8,27 +8,7 @@ includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 ["UTC", "+01:30"].forEach((timeZone) => {
   const result = Temporal.ZonedDateTime.from({ year: 2000, month: 5, day: 2, timeZone });
   assert.sameValue(result.getISOFields().timeZone, timeZone, `Time zone created from string "${timeZone}"`);
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/equals/argument-propertybag-timezone-string.js b/test/built-ins/Temporal/ZonedDateTime/prototype/equals/argument-propertybag-timezone-string.js
index 5925d5a045..c6df5823b2 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/equals/argument-propertybag-timezone-string.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/equals/argument-propertybag-timezone-string.js
@@ -4,32 +4,12 @@
 /*---
 esid: sec-temporal.zoneddatetime.prototype.equals
 description: Time zone IDs are valid input for a time zone
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
 
 const instance1 = new Temporal.ZonedDateTime(0n, "UTC");
 assert(instance1.equals({ year: 1970, month: 1, day: 1, timeZone: "UTC" }), "Time zone created from string 'UTC'");
 
 const instance2 = new Temporal.ZonedDateTime(0n, "-01:30");
 assert(instance2.equals({ year: 1969, month: 12, day: 31, hour: 22, minute: 30, timeZone: "-01:30" }), "Time zone created from string '-01:30'");
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/round/rounding-is-noop.js b/test/built-ins/Temporal/ZonedDateTime/prototype/round/rounding-is-noop.js
index 65096c44bc..7eed8b48e1 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/round/rounding-is-noop.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/round/rounding-is-noop.js
@@ -3,16 +3,11 @@
 
 /*---
 esid: sec-temporal.zoneddatetime.prototype.round
-description: >
-  No calendar or time zone methods are called under circumstances where rounding
-  is a no-op
-includes: [temporalHelpers.js]
+description: Circumstances where rounding is a no-op
 features: [Temporal]
 ---*/
 
-const calendar = TemporalHelpers.calendarThrowEverything();
-const timeZone = TemporalHelpers.timeZoneThrowEverything();
-const instance = new Temporal.ZonedDateTime(0n, timeZone, calendar);
+const instance = new Temporal.ZonedDateTime(0n, "UTC");
 
 const noopRoundingOperations = [
   [{ smallestUnit: "nanoseconds" }, "smallestUnit ns"],
@@ -23,11 +18,3 @@ for (const [options, descr] of noopRoundingOperations) {
   assert.notSameValue(result, instance, "rounding result should be a new object");
   assert.sameValue(result.epochNanoseconds, instance.epochNanoseconds, "instant should be unchanged");
 }
-
-const notNoopRoundingOperations = [
-  [{ smallestUnit: "microseconds" }, "round to 1 µs"],
-  [{ smallestUnit: "nanoseconds", roundingIncrement: 2 }, "round to 2 ns"],
-];
-for (const [options, descr] of notNoopRoundingOperations) {
-  assert.throws(Test262Error, () => instance.round(options), `rounding should not be a no-op with ${descr}`);
-}
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/until/argument-propertybag-timezone-string.js b/test/built-ins/Temporal/ZonedDateTime/prototype/until/argument-propertybag-timezone-string.js
index 2e49c2d59e..591fd3db7d 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/until/argument-propertybag-timezone-string.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/until/argument-propertybag-timezone-string.js
@@ -4,32 +4,11 @@
 /*---
 esid: sec-temporal.zoneddatetime.prototype.until
 description: Time zone IDs are valid input for a time zone
-includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 const instance1 = new Temporal.ZonedDateTime(0n, "UTC");
 assert(instance1.until({ year: 1970, month: 1, day: 1, timeZone: "UTC" }).blank, "Time zone created from string 'UTC'");
 
 const instance2 = new Temporal.ZonedDateTime(0n, "-01:30");
 assert(instance2.until({ year: 1969, month: 12, day: 31, hour: 22, minute: 30, timeZone: "-01:30" }).blank, "Time zone created from string '-01:30'");
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/withTimeZone/timezone-string.js b/test/built-ins/Temporal/ZonedDateTime/prototype/withTimeZone/timezone-string.js
index d99aed5767..f01e774f73 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/withTimeZone/timezone-string.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/withTimeZone/timezone-string.js
@@ -8,29 +8,9 @@ includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const getPossibleInstantsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getPossibleInstantsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getPossibleInstantsFor should not be looked up");
-  },
-});
-const getOffsetNanosecondsForOriginal = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor");
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", {
-  configurable: true,
-  enumerable: false,
-  get() {
-    TemporalHelpers.assertUnreachable("getOffsetNanosecondsFor should not be looked up");
-  },
-});
-
 const instance = new Temporal.ZonedDateTime(0n, "UTC");
 
 ["UTC", "+01:30"].forEach((timeZone) => {
   const result = instance.withTimeZone(timeZone);
   assert.sameValue(result.getISOFields().timeZone, timeZone, `time zone slot should store string "${timeZone}"`);
 });
-
-Object.defineProperty(Temporal.TimeZone.prototype, "getPossibleInstantsFor", getPossibleInstantsForOriginal);
-Object.defineProperty(Temporal.TimeZone.prototype, "getOffsetNanosecondsFor", getOffsetNanosecondsForOriginal);