My seatbelt rule for judgment
I feel that I made the transition from jr to mid level developer when I was able to come into some new code and judge it, instantly pointing out what was wrong and how it could be improved, and how it should've been built. I feel that I went from mid to senior when I would enter that same situation and try to understand the why behind the code (even though I probably still thought it was poorly architected) before passing judgement or trying to "fix" it with a refactor.