Exactly. Spaced repetition is a remarkably effective learning technique, but it can't tell you what to learn.
At some point I think we have to stop listening to external authorities and rely on our own judgement about what to learn, and how to do so, as signalled by feelings of excitement about particular authors and ideas. One of the effects of formal education is to dampen or corrupt that intuition, e.g. by instilling the desire to learn things 'properly' (say in a certain prearranged sequence) or by the desire to only learn prestigious topics in order to impress other people.
If we are engaged meaningfully with reality we will inevitably revisit particular subjects or authors multiple times. This is an organic form of spaced repetition. Forgetting certain things is part of that: we learn to swim during the winter and to skate during the summer.