Sorry for replying late. I understand what you are asking; but the driver should be time allocation mechanism you are following. You might know all questions are important on the test and hence you need to decide how much time you should spend on each one of them. I would say you should not check your answers repeatedly since you will lose valuable time. You should learn to move forward.

My strategy is usually to check my answers if I did a problem pretty fast - say, under a minute - just to make sure I didn't miss something or make a silly mistake. Also, I might check my answer on earlier questions since they theoretically count more. However, I'd never check my answer more than once; that's a time killer.

This is a very personal decision that depends a lot on your own personal pacing. I, for example, know that I usually have 10 minutes or so to spare on quant so I feel okay taking my time on a few questions. Some people struggle to even get to question 30 - those people obviously need different pacing strategies than I do.

That's why practice tests are so important. Make sure you have a clear idea of your own pacing before the "real thing" - if you always double check your answers and you still finish the test on time, then it's probably okay to check your answers on the test. If you always have trouble finishing, you might not want to check your answers (or at least all of them).

Good luck!