Hm, I have never made much notes (mostly none), from my point of view, lectures are useful to get a rough idea about the subject, or "what should I really learn

Hm, I have never made much notes (mostly none), from my point of view, lectures are useful to get a rough idea about the subject, or "what should I really learn", and then there are textbooks, monographs and other sources to study thoroughly (alone). OK, mostly I wouldn't visit the lecture anyway, as it tends to be either boring or crowded, and so on. Powerpointesque presentation for the lectures are useful as a list of the topics mentioned in the lecture.