Forgetting is part of the method

Memory sets in right when you're about to forget. That's why reviewing ten times on the same day yields far less than reviewing five times spread across a month.

The phenomenon has been measured since 1885, when Hermann Ebbinghaus memorized thousands of nonsense syllables and drew the forgetting curve: without review, much of what you learn vanishes within days. Each spaced review flattens that curve, because effortfully retrieving a memory makes it more resistant.

A century later, a meta-analysis pooling more than 300 experiments confirmed it: spacing sessions out beats cramming across almost any subject and time frame. The practice is simple: review the next day, after three days, after a week, after a month. Let forgetting begin its work, and interrupt it.

Source: Cepeda et al., Psychological Bulletin (2006)