Depending on the class, there are some that teach more to the boards and some that teach random little facts (although I did have some minutia show up on my board exam that I wouldn't have known otherwise). Generally you'll want to do well in classes. Supplement second year with pathoma, first aid, sketchy, firecracker, and UWorld. During M2 year, classes end early May with some NBME exams scheduled until the middle of May. You have until clerkships begin to take STEP1, which I think is early Julyish. If you take STEP1 early, you get a long break.