The ten minutes after the lecture

The highest-return habit in this whole area is ten minutes immediately afterwards, filling that empty margin: what was the main claim, what did I not follow, and one question I would ask. Ten minutes now saves an hour in April, because you are repairing the notes while you still remember what the gap was.

Mark what you did not understand explicitly, using a symbol you always use. Unmarked gaps quietly turn into things you assume you knew, and they reappear in the exam as a topic you cannot begin.