1.) I would suggest that you don't do any new questions. However, you may want to focus on reviewing select practice questions you got wrong. As I went through my various Qbanks and the such, I marked the questions that I got wrong that left me with an "ahh haaaa!" feeling. Then I reviewed them, understood why I got them wrong, and reinforced the learning objectives that underlie them. Of course, I didn't focus on the stupid, nit-picky practice questions that I got wrong (aka a lot of Kaplan's stuff), only the ones that I marked and felt were important.... anyway, I did this a few times during the last week, and did this once more the day before.
2.) Of course, reviewing a lot of questions you got wrong might be somewhat damaging to your nerves and cause some anxiety. In general the day-before is a very nerve-wrecking time anyway. To help limit test anxiety and to reinforce your confidence, it can be helpful to review your study progress. The day before I wrote out all my practice score equivalents on a sheet of paper and looked at my performance progress. Meanwhile I kept thinking to myself, "I can do this, I can do this." Sorta like a mantra. Anyway, looking at my most recent NBME results really boosted my confidence and calmed my nerves. If I wind up getting anything near those results I'd be very happy!
3.) Although it's sorta late to cram any new information in, it doesn't hurt to look over some familiar stuff one more time. The week leading up to my exam, I typed up some 50 pages of listed, "high-yield" testable material in all the major disciplines. Stuff like key drug-drug interactions, selected drug of choice, signature drug toxicities, biochem rate-limiting reactions, biochem enzyme deficiencies and what substrate accumulates, vitamin deficiencies, serum tumor markers, key regulators of the cell cycle and oncogenes/tumor-suppressor genes, HLA associations, autoimmunity antibodies, anatomy clinical manifestations for various lesions, etc. etc. Although FA clearly has a lot of this already written in there, I found it helpful to type it up myself after reviewing the material from Kaplan and other sources. Then the night before I pretty much read through my own lists, and I thought about how or why these things might present clinically. The whole time I would think, "who gets this? what would a patient with this look like? how would you diagnose it? what treatment option is best? what will prognosis be like? what is the mechanism underlying the disease?"
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Well hope that helps. I don't subscribe to that school of reasoning "do nothing the day before"... that's just not how I do things. On the other extreme is "cram everything!!", which doesn't work either. Somewhere you have to draw the line and realize that for this test, no-one is ever absolutely 100% ready, everyone has at least "one more thing" to review... that's the whole point. You're gonna see stuff on this thing that you never saw before. They test more than what you know; they test how you think, they want to see your reasoning process. That's why point #1 above is so important.
Well good luck, stay calm and take it one question at a time ^_^