Using Practice (spaced repetition)

Practice, in the navigation bar, resurfaces questions you've previously missed on a spaced schedule — 1, 3, 7, 14, 30, then 90 days out — so they move into long-term memory instead of being forgotten.

It pools questions across every book you have access to, so there's nothing to pick — just open it and go. If nothing is due, you're already caught up.