These things made me feel like I was learning. Flashcards and notetaking itself were fun games. I felt like I'd stumbled onto this hyper-optimized efficient way to learn whatever I wanted.
That feeling was misplaced.
I threw away all that garbage and just started diving into things after reading/observing the bare minimum to get the wheels rolling. Read a little, act a lot. The acting is the most important part. You want to learn some thing? Just do that thing, repeatedly.
It's inefficient, failure-laden, and it's the best way to truly learn something.
This applies to abstract things too, like math and language. Don't bother making flashcards for theorems, syntax, or word definitions. You gotta do the work. For math, just do a million exercises. For language, read, write, listen, speak. You can flashcard word definitions and atomic little rules all day, and you'll feel like you're making progress, that's how Duolingo reels in so many people. It's an easy way to feel like you're accomplishing, but it's a facade. Gotta just do the work.