Hi abcd,
Indeed - timing is and psychology is a critical element to the GMAT exam that a lot of people overlook.
You have to train for GMAT the same way you might for a mental marathon. Questions just keep coming at you and you need to consistently pound them out without hesitation.
Try visualization - a lot of top athletes do this. When you are studying, imagine you are actually sitting in the exam room. It's completely quiet--there are other people around taking other kinds of tests. Your job is to ace the test on your computer - the GMAT. Give yourself a few sections before you attempt a GMAT question during study time - and imagine you are in that mental mode. Then go ahead and attack.
Once you get into the habit of better understanding and feeling your test environment, you'll get more used to the feeling and will be better able to concentrate.
For more details, see this link:
https://www.gmatpill.com/about/studying- ... trategies/