This is an oddly effective right-brain activity that works well with left-brain tests.
How many times have you encountered a science or math question on an exam that seemed as if you were close to it...it's on the tip of your tongue (so to speak)...but you just keep waffling. This is particularly dangerous on a multiple-choice question. There are usually two wrong answers. Get rid of them immediately. Then, you usually find yourself going back and forth between the correct response and one that looks like it's suspiciously a great lead. The latter is called a "red herring", and it's intentionally designed to confuse you (no, it's not your imagination). So, go with your first instinct. It is often the correct one. If you don't have any truly compelling reason - such as the right answer suddenly striking you across the forehead by a cosmic 2X4 - then you shouldn't start changing answers.
I can't tell you how many times people have second-guessed themselves out of a right answer, due to not following this simple advice. They want to go into a corner and cry when they get the test back and see what they had done. Stop that right away; and do your best. Go with your first instinct. It's often right.