Rule of thumb: write more spaced repetition prompts than seems natural

Most people tend to write a smaller number of larger prompts, likely because of small frictions in the authoring interfaces and because they don’t understand that prompts are cheap (Spaced repetition memory systems are extremely efficient). Prompts seem to carry a per-unit “price,” so people naturally try to write fewer questions which cover more ground. But that’s counter-productive. Unless you explicitly decide to exclude certain information, the number of “units of raw knowledge” is fixed, a constant of the territory. When you write coarser prompts in smaller quantity, you’re not reducing the amount you have to learn. You’re just making the material harder to review.

Prompts are cheaper than you probably imagine. An easy prompt will consume 10–30 seconds across the entire first year of practice, and much less in each subsequent year. Until you’ve internalized that observation, try to adopt this rule of thumb: write more prompts than feels natural.

This rule is a natural consequence of Spaced repetition memory prompts should usually focus on one atomic unit, Spaced repetition memory prompts should encode ideas from multiple angles, and Spaced repetition memory prompts should connect and relate ideas.

Now, prompts are cheap, but they’re not free. Besides their time cost, they have an emotional cost: no one wants to spend time reviewing a bunch of boring material they already know. So if you’re writing prompts for a subject that’s already quite familiar, you should use fewer prompts—not because it’s always safe to write coarser questions for familiar topics, but because there’s less marginal knowledge you need to capture.