As you said, unfortunately, there are things that you need to know to be a good student and eventual doctor (i.e. part of them being your med school lectures/exams) and there are things you need to know to score high on standardized exams (i.e. memorizing FA, etc.) and these two things overlap but there are significant portions of each that don't.
My advice is to have priorities regarding what to focus on. I encourage prioritizing your school studies/assignments and fill in any free time you are willing to volitionally do the other stuff. Over the course of M2, these priorities may shift and you might be doing the bare-minimum for school and spending more time on board-specific stuff. At the end of the day, this time (pre-clinical years) is the time to build a good medical knowledge foundation... and you will not have time to do this again (unless you take time off or something which you shouldn't do just to "restudy" stuff...) so keep that in mind.
I will leave you with two anecdotes that I will have you analyze instead of me putting my thoughts in your head:
1. There was this below average med student in my class and he completely disregarded school stuff during M1 and M2 year and solely focused on Step I. If something wasn't related to step I, he didn't care. He ended up killing Step I, but marginally passed M1 and M2 year--consistently being on prohibitionary status. He tanked M3 year because he didn't like the real world and his same "if it's not on exams, I don't care" attitude carried over. He ended up almost not matching.
2. There are always several students that fail the last M2 exam because they spent too little time actually learning the material (which also is on Step I) and only focused on boards. They had to do a make-up exam before they took their board exam...not good.
All in all, do what you want, but please remember the utility of what you're doing and what you want to get out of it. This has been said many times, but the first thing to do to do your best on Step I is to grasp the material and do well in your first and second year. It is an investment (in many ways) that will pay out--not only for Step I--but for the rest of your career.
FS