I've done 2 grad semesters of QM and 2 grad semesters of Mechanics. I've kept my math reasonably up to date due to my job. My contour integration is weak, but my differential geometry, linear algebra, and PDE skills are still fairly sharp.
I was a denizen of this forum some 15 years ago during undergrad. However I since joined the dark side working in software on ML, AI, and distributed data processing.
Every now and then I pick up a physics textbook to get into the weeds of a topic I would have missed due to skipping out on grad...