Writing as somebody whose day job includes teaching University students and assessing their performance in exams or other tests, I think that giving yourself feedback about how well you understand a topic is very important.

It is easy to read over lecture notes, handouts, etc in a vague way, thinking "Cool, I understand that." which may or may not be true.

What I advise my students to do is, once they think that they understand a topic, to put away their notes about it and write down all that they know about it.

Once they have done that they can get feedback by comparing what they have written with what is in their notes.

That feedback might be: (1) "Yep, I understand that." or (2) "OK, aspect X of the topic was covered well but you forgot about aspect Y." or (3) "You need to do a lot more work.".

That feedback helps them to work out where to focus their time in preparing for a test or exam.