Spaced Repetition Turns Misses Into a Schedule

"Distributed Practice"

Spacing works because memory decays. Ebbinghaus described the forgetting curve long before modern apps existed, and Cepeda et al. later confirmed that distributed practice reliably outperforms massed practice across domains.

The practical consequence is not abstract. If a candidate misses evidence on Tuesday, drilling evidence again on Tuesday night is not the same as resurfacing it after the memory has cooled. The second version asks the brain to recover the rule from a weaker trace, which is exactly what makes the trace stronger.

Vrenberg uses that logic in the review queue. Missed rules do not disappear into a generic history log. They reappear on a schedule that expands when performance improves and compresses when performance slips.

What that means in the product:

• The engine treats decay as a feature, not a bug.
• Review timing is driven by mastery, not by a fixed calendar.
• The learner sees rules again right before they are likely to be forgotten.

That is why spaced repetition is not a bonus feature here. It is the mechanism that makes the rest of the system stick.

Sources
Ebbinghaus, H. (1885). Uber das Gedachtnis.
Cepeda, N.J. et al. (2006). "Distributed Practice in Verbal Recall Tasks." Psychological Bulletin, 132(3), 354-380.