Comment by kqr

Guessing from personal experience, I would not be surprised if 70 % of the domain knowledge is learned in the process of writing and modeling.

Whenever I encounter a tricky subject I'm having a hard time learning, I start writing an article explaining it to someone else. It really forces me to confront the gaps of my knowledge because I can see so clearly that "Wait, I can't explain what happens between these two steps here. What am I missing?"