OP, I hope that you have noticed that there are quite a number of different views of what resources are useful. To that end, you need to find what works for you.
Also keep in mind that what worked n UG probably will not work in med school, due to the sheer volume of material.
Read this:
Gawd, whenever I hear my students say this, my superior rectus muscles go into spasm from my rolling my eyeballs. We once had OMSIs (Is!!!) complaining that a particular subject in OMSII was going to have ~ 6 hrs of coverage, and that wasn't going tobe on COMLEX. "Do we really need 6 rs on X???!! Every clinician said "yeah, you do." In addition, I wrote questions on that material for NBOME.
For some people group study is a waste of time, probably because it's too distracting or people can't focus. But I have noticed for a long time that my weakest students
tend to study by themselves (or with other weak students). When they switch to a group with strong students, their grades tend to improve.
I'm not an education PhD, but with but we do tend to pick up on what weak students do, and what good students do. One doesn't have to be a chicken to comment on the quality of eggs.
If any professor is teaching about their research instead of the material, burn them at the stake. Ditto those who always say "it's in the book" when you ask them for specifics on what to study. Pin them down figuratively, and if they still aren't helpful, then literally.