I think the phrase in the education literature is mastery learning: my exposure to it was discussion of how Khan Academy does math tests. Because they're on a computer-based system, they can generate an arbitrary number of problems of a particular form (like, for example, 'multiply two three digit numbers together') and give each student as many problems as it takes for them to get 10 right in a row. Sometimes the student gets the lesson and only does 10 questions; sometimes the student takes 200 tries to get 10 right in a row, but they always master the skill before they move on (or they spend a lot of time getting very lucky).