It's really up to you. Some schools offer class discounts for Qbanks so if that's the case you're kinda stuck with the one you get. And if your school doesn't offer one, and you want to look into it, usually if you can get 100 people to commit to buying you can swing at least a 10% discount. Definitely worth putting a google doc together and letting people sign on since you're all going to be buying it anyway.
Personally I used Kaplan Qbank intermittently throughout the year along with our systems-based curricula, then got UW for my study period. I didn't get all the way through (I think about 9% unused), but I was able to make it through all the Qs I had missed again.
Note-taking on questions and reviewing those notes can really help solidify concepts, especially if you've been doing questions all along. The major benefit to doing questions all year is that you'll get yourself into the mindset of how to tackle questions. Many school exams rely on rote memorization for a good portion of the exams, but that doesn't always cut it for the USMLE. Also those notes come in handy for those last two days before the exam where you really want to stop staring at a computer screen but also don't want everything you've learned to fall out of your head
Ultimately since I learn by engaging in questions and exploring the answer choices and learning why the answer is right and what makes the other options wrong, doing mostly questions was what worked for me. You have to figure out what your learning style is.
Biggest piece of advice: don't let other people freak you out. You can't use every resource (I know people who bought Kaplan lecture notes or three new books halfway through their study period only because other people were doing it). Pick your methods and stick to them, and try not to question yourself if you're getting the trends you want. And of course continue to ask questions from the people who are pros on here who frequent these message boards much more often than me
We'll see how it went in three days. This wait has been killer.