One classic piece of advice from Piotr Wozniak - Effective learning - Twenty rules of formulating knowledge is that spaced repetition is best used to help you reinforce something you have already understood. Think of it as a way to “save state”—you have to be in a sufficiently good state before you apply the practice technique.
Mechanistically, I think this is true because Mnemonic medium prompts rely on invoking external experiences (from narrative, from real-world experience). The prompts you review don’t fully “cover” the topic—not enough to learn from them anew—but when you review each prompt, you also reinforce (less strongly) other “nearby” information, which collectively covers much more of the topic. But this is only possible if you understood the topic well enough before reviewing to form well-connected knowledge. Without that, you’re just reinforcing the details you’re reviewing, in isolation.
Generally speaking, memory prompts don’t communicate well on their own, anyway: Spaced repetition memory prompts alone are a poor communications medium.