I had a similar (or identical?) experience with engineering. I "learned" much of it in school. Some of it was really challenging, and I quite frankly, did not u

I had a similar (or identical?) experience with engineering. I "learned" much of it in school. Some of it was really challenging, and I quite frankly, did not understand it well. What's odd is that I put in a lot of effort in school. But it didn't stick. I just couldn't get it all. Fast forward 16 years. I spent 6 years as a practicing engineer, followed by 10 doing other things. But now when I look back at a book that I had trouble with in school, it seems very straightforward. I've forgotten some of the math, but in general, everything is easier now. Is this because learning this sort of thing takes time to sink in? (I did not actively study engineering after quitting my engineering job). Is it a matter of context? Things to compare the concepts to? Or even biological age? Also interesting that I have not found this to be at all the case with programming, which I learn much like anything else - a bit at a time with no "leaps" in understanding.