Each subtest is timed and, on the computerized version of the ASVAB, that’s the only time you’ll get for that subtest. On the paper version you can go back and check answers on previous subtests but, on the CAT-ASVAB once you complete a subtest your answers are set in stone and you can’t go back to review.
So, it’s very important to both know how long you have for each subtest and to have taken enough practice tests to know how long that subtest will typically take you. That way you’ll have a good understanding of how much time to spend on each question and what pace you need to maintain to get through the subtest in the time allotted.
Also, make sure to take practice tests under actual testing conditions – use a timer to make sure you’re not taking additional time to complete the practice test that you won’t have available at the real test.
Don’t spend too much time on one question. If you draw a complete blank make an educated guess and move on. You’re not expected to get every question right and the more time you waste on questions you know you don’t know the greater the chance that time will run out leaving questions you could have potentially answered correctly unanswered.
The best way to overcome time anxiety is to take practice tests to gain confidence that you have enough time to complete the test and to be focused on moving through the subtest. Answer a question, check your work, then move on and erase that question from your mind.