Memory and Decay — Map of Content

Most products model capability as something a user banks: they completed it, so they have it. They do not have it. From the moment of acquisition it is decaying, on a curve that differs per item and per person, and a product whose value depends on retained capability needs a maintenance loop rather than only an acquisition funnel.

This skill owns one decision: when to bring something back in front of a user. It does not own how hard the next item should be for that user — choosing when an item returns and choosing how hard to make it are different models, and difficulty belongs to the difficulty-calibration skill.

This skill is a graph: scan the descriptions, follow only the [[wikilinks]] you need.

How memory actually behaves

• [[references/spacing-beats-massing-at-equal-cost]] — the same repetitions spread across days survive; massed into one sitting they buy a passing score and nothing else. Frequency is the parameter, not length.
• [[references/sleep-is-a-free-consolidation-pass-you-can-skip]] — traces migrate to long-term storage overnight, so a one-block schedule deletes passes the user's brain would have run for free.
• [[references/decay-is-graded-and-fine-grain-goes-first]] — specifics rot fast, structure is durable, recognition outlives production. Decay is a shape, not a switch.

Scheduling: what comes back, and when