I'm taking my qualifying exam next Friday and I'm wondering what I should do the day before to help reduce my anxiety. Do you recommend last-minute studying or taking the day off to relax and reflect?
There is no universal answer to this question, because different people find that different techniques work well/badly for them, and they also have different levels of aptitude for rapid learning and short-term knowledge retention. In my observation, most successful students use a range of methods to varying degrees, depending on their particular aptitudes and learning styles. Here are some common elements of effective preparation, including advice on your particular issue:
Don't slack off too much during the semester: While this is not strictly a method for what to do in the short period before your final exam, I would be remiss if I didn't include it. If you put in a reasonable amount of effort to learning the course material during the semester, and keeping up with the topics, you will enter your study period with most of the material already known to a reasonable level. In this case your sole job during the study period will be to refresh your knowledge and fill in any small blanks where you have had previous difficulties. Using your semester for effective study will significantly reduce anxiety in the study session and exam period.
Do your study sessions a reasonable time in advance: It is important to leave yourself a reasonable amount of time before your exam to start intensive study. If you have studied well during the semester then much of this will just be review, but if you have been a bit lazy during the semester then you might need to "cram" a substantial amount of new content. In the latter case you should leave yourself at least a week, depending on how effective you are at rapid learning and knowledge retention. Over a few exam periods, you can track your rate of progression over your topics in each course and use this to judge how much time it takes you to study effectively for a single exam. As you gain experience you will be able to judge how much time you need to leave yourself and what volume of material you are able to effectively "cram" in the study period before your examination.
Relaxing activity the night before the exam: Many successful students try to avoid cramming right up to the exam, since this can impose stress/loss of sleep that can impact negatively on exam performance. Consequently, one good technique is to do your studying in the week before the exam but do a relaxing activity (not involving alcohol) the night before to destress --- e.g., go and see a movie at the cinema. This allows you to decompress and relax for the evening immediately prior to your exam.
Reviewing notes immediately before the exam: It is usually useful to do a review of your notes in the hour or two before an exam, to bring concepts and methods you will need back into your short-term memory. At this point you should not be "cramming" to learn new material, but you should be jogging your memory of all the things you might need in the exam. For this part it is usually sufficient to go over points in your notes at an overview level for about an hour; depending on your abilities and the quantity of material it might be less or more.
I hope "next Friday" means in a week, not in a day.
Cramming is usually the worst option. Staying up late the night before also.
There is a danger in late study that the mind may not have had enough time to let the late studying "settle in" so that it doesn't block things studied earlier. A qualifying exam doesn't normally depend on having a bunch of quick facts at your fingertips.
Everyone is different of course, but I doubt that hard study at the last moment will reduce stress. Quite the opposite.
But spending some time the day before the exam doing some aerobic exercise can let your mind relax while your body works. Bicycling was my drug of choice. I found it great as a stress reducer.
I'd guess that if you don't know the material two days before the exam, hard study the day before the exam isn't going to save you.