Spaced Repetition is a scientific method of learning that involves time intervals between subsequent review of learned items to exploit the psychological effect of spacing effect.
A meta-analysis by Donovan and Radosevich, in 1999 suggested that those who learn information by spaced repetition will outperform 67% of those who learn by mass presentation given the same number of practice episodes.
Spaced Repetition Practice Tools .
Donovan, John & Radosevich, David. (1999). A Meta-Analytic Review of the Distribution of Practice Effect: Now You See It, Now You Don’t. Journal of Applied Psychology. 84. 795-805. 10.1037/0021-9010.84.5.795.