I disagree. To be fair, I used to think this too, but then when I started to actually used spaced repetition in the process of learning more complex subjects I

I disagree. To be fair, I used to think this too, but then when I started to actually used spaced repetition in the process of learning more complex subjects I became surprised by how much more fluid my reasoning became. Writing good flashcards is about - noticing similarities and differences, - exploring variations of a concept, - finding generalisations of related concepts, - learning properties of a concept, etc. All these things are things you use when reasoning also about more complex ideas. In other words, spaced repetition is an efficient way to raise the baseline for what counts as a "fundamental fact" which makes it possible to think at a higher level of abstraction.