Revisit a topic often enough that retrieval is effortful but still possible. Reviewing too soon can create false ease; waiting until everything is forgotten makes each session feel like starting again.
Use shorter intervals for new or weak material and widen them as recall becomes more reliable. The exact spacing should depend on performance: if you can retrieve and apply the idea accurately after a delay, the next interval can grow. If it collapses, shorten the gap and repair the weak part.
Use Revision Scheduling — When Should You Come Back to a Topic? for the deeper method, and the Study & Learning Methods Hub for the wider revision system.