yeah, I was lucky to have already taken Classical Mechanics prior to Quantum Mechanics (it wasn't a prereq so most of my classmates jumped straight into QM), so the math was all perfectly sensible. but the second any prof started trying to use English to interpret the math, I started having these moments where I'd have to sit back and think about the words coming out of their mouths, and sitting with how it was all actually gibberish. Feynman's "shut up and calculate" started to feel incredibly valid really fast, whereas prior to QM, I was under the impression that physics was natural philosophy. it's not and QM was the breaking point, at least for me, personally.