I may have well thrown away my notes! I often times had inaccuracies as I fell behind instructors (seriously how fast can they write on blackboards!?) and lost important context which made sense at the time but not later.
But you are correct, writing things down helps commit things to memory, plus there were always some funny doodles to look back on. Too bad I can't doodle anymore in work meetings, it isn't too professional :(
Looking back, the purpose of the lectures was to give a general overview of the themes and boundaries of the course. You note that down. Then go read the textbooks and do exercises to actually learn the material. As you say, in a fast paced technical class you cannot rely on learning the material in lectures.
But you are correct, writing things down helps commit things to memory, plus there were always some funny doodles to look back on. Too bad I can't doodle anymore in work meetings, it isn't too professional :(