No OP, but Anki is an app that you can use with your own custom flashcard packs, or find them online. You review a card and mark how well you remember it, with the hardest ones resurfacing more quickly and easiest ones more seldom.
Spaced repetition is more efficient because it is based on refreshing something in your memory at the (theoretically) optimal intervals to transfer it from short-term to long-term memory. So at any time, the app should surface the cards you need to see the most.
It does actually work and isn't pseudo-science. It got me through the bar exam after law school.