Which of the following would NOT be a common metric used for monitoring test preparation...

Common metrics used for monitoring test preparation and execution typically include quantitative measures such as the number of test cases passed and failed, the percentage of planned test cases designed, and the percentage of tasks completed in test environment preparation. These metrics provide insights into the progress and effectiveness of the testing process. However, the number of test plan review comments is not a typical metric for this purpose, as it does not directly measure the progress or quality of test execution​​.