> It also just seems like there's a huge random element, like am I debugging code written by somebody who thinks at the same level of abstraction as me? Did they write comments I understand?

Isn't that part of what professional software engineering is about? Unless you worked with the same group of people for a decade and have had the time to mind meld together professionally, _any_ random developer at a new company is nearly guaranteed to think in a different way and have their own philosophy of code comments.

Checking for mental flexibility and adaptation to varying approaches for others is a great subject for an interview as a software engineer.