How to study better for graduate level courses?

Hi all! So I am minutes away from my final and pretty sure I am about to fail this exam. For some reason, I just haven't been able to get a handle on my work all semester, for a variety of reasons. It feels like the courses are set up that we should do 1-2 problems on a topic in a pset and then "understand" via the derivations we did the physics and be able to apply it in new ways on the exam.

My past study habits included reviewing example problems, doing extra problems with solutions if I can find them, and going to office hours. So, that doesn't really jive well with the new expectations-- it's worked more or less in some classes like statistical mechanics, less well in others like electrodynamics, and not at all in advanced quantum mechanics. The problems also take many hours per problem, so I can't really "drill" them like I used to.

It feels like I just need to radically change my approach somehow. Additionally, my university is stuck up and elitist, and pride themselves on their grad students being "self learners" so getting any help with courses is pretty strongly discouraged and my requests for help from professors were already denied. So, whatever this new approach is, it needs to be a self-sufficient one.

I may be required to do the course over, and if not, I will at least struggle a lot on qualifying exams. Any advice welcome!!