There are people saying here that is not worth it. I tend to agree but for different reasons. Flashcards with spaced repetition can help you learn mathy concepts, as Michael Niesel and others have shown.
As high_derivative notes, to make the process worthwhile, you need to make the notes yourself in order to internalize chunks that are worthwhile to you. That means your own definitions that you are failing to remember, the questions you need to answer, the problem sets you want to review, etc.
You can only internalize with a method like flashcards w/ spaced repetition once you understand the argument, need, and narrative.
As high_derivative notes, to make the process worthwhile, you need to make the notes yourself in order to internalize chunks that are worthwhile to you. That means your own definitions that you are failing to remember, the questions you need to answer, the problem sets you want to review, etc.
You can only internalize with a method like flashcards w/ spaced repetition once you understand the argument, need, and narrative.