Hi Mathbro,
Yes, you should scrutinize every answer choice during practice, as this habit is critical for building your ability to quickly and confidently identify correct and incorrect options.
While it may feel time-consuming, especially when a question takes 2.5 minutes or more, this effort is not wasted. It helps you recognize common traps, patterns, and reasoning flaws, improving efficiency. During practice, even if you feel highly confident in your selected answer, spending extra time analyzing why the other options are incorrect is beneficial. This process will help you develop a more systematic approach, allowing you to quickly reject incorrect choices on test day.
If questions currently take you 4-5 minutes in practice, that's okay, as the goal now is skill-building, not speed. Over time, as you refine your reasoning and confidence, the time you need to spend per question will naturally decrease.
For some more CR advice, here is a great article to check out:
GMAT Critical Reasoning: 8 Essential Tips