In my good old maths undergraduate days, in many courses the notes were what was written on the blackboard in lectures. No handouts or slides. There might have

In my good old maths undergraduate days, in many courses the notes were what was written on the blackboard in lectures. No handouts or slides. There might have been a relevant textbook, but its contents would not be exactly the same as the course. So my default mode was to copy absolutely everything down (using my own personal set of abbreviations) whilst not necessarily understanding everything. Occasionally I would understand everything in the lecture; occasionally I would understand nothing in the lecture; usually it would be somewhere between the two. Later I would copy out my notes neatly, but not allowing myself to write anything into my neat copy until I understood it. If it took me a long time to finally see how a step in a proof was justified, I would write the justification into my notes. If I had to revise something to understand the new material, I would write the relevant points I had forgotten into my notes. Hence reading my notes to revise for the exam could be as fast as possible. To the extent that I perfectly carried out the above system, I gained near to perfect marks. To the extent that I didn't carry out the system, my marks suffered.