I'm curious if the test penalizes a user more for leaving blank answers at the end than it does for rushing and guessing wrong answers.
IE: you have 2 minutes left and 5 answers--do you rush and guess all 5 answers or should you spend a minute on 2 and get them correct, but leave 3 blank?
I don't know point-wise, but you probably should try to get some of the 5 right - see the first one - how long it will take and if it is more than 50% of time, guess and move on. WHen you get to the last question - pick an answer - any answer - so that if you run of time, you would have a recorded answer - GMAT will ask you if you want to record it even though you ran out of time. So when you are on #37 or 41 - always pick one of the choices - just randomly - they if you get a better idea while there is time - adjust the answer selection.