Whichever way keeps your focus and works for you. One option that I prefer (studying for any test) is to do a quick skim of what is on a test (for example I might just spend an hour skimming the AFOQT guide) then do a practice test. Look at the areas I did not do well in (using the results) and use that as targeted feedback. Focus on those areas in which you did not do so well while studying, whether that is reading a review guide, watching YouTube videos on the subject, etc. and then retake a practice test. Rinse and repeat. Just one option of many. Again, it’s whatever rhythm and strategy that works for you.