[PaulHoule]

Taking notes from books is for the birds, you can always go back to the book. The counterexample to that is you might be writing some kind of critique or analysis and this is your first draft -- in this case you might want to record your emotional reactions or personal experiences relevant to the text, citations to other works that are related, the results you get "reading between the lines". etc.

Taking notes from lectures depends on the course. You can't go back to the lecture, plus you might believe it's a guide to what is on the text. It depends on how much is the whim of the teacher. In a lit class, take notes. If it is introductory chem you can probably get it all from the book and the problem sets. [1]

When you're doing original research though, it is all about the notes. I filled up about 30 notebooks in the process of getting my PhD, you really should document every little thing that you try.

People do it less but you should do the same if you are doing any kind of engineering. Not least if you want to file a patent you want your whole invention process documented so you can prove you invented it.

Even in programming you should keep a notebook of your thought process and debugging. Personally I find I write better quality code when I work with an LLM because it forces me to take better notes.

[1] I wound up taking intro chem when I was a senior and a better student and got the top score in the class even though I rarely attended it. It did get a tiny bit of help: the prof told us we could skip one quiz, I did, then went to the chem lab to ask the T.A. to skip the test, he said "Why not take it right here?" and he looked at it and handed it back to me and said "Are you sure about that?" I thought it through again and realized my mistake.