This mistakes the purpose of school. It’s less learning than childcare for primary school, socialisation and teaching children to do apparently boring and meaningless work as directed by superiors, and ranking and proof of intelligence and conscientiousness at higher levels. We’ve known most people forget almost everything they learn at school for a very long time and spaced repetition and the forgetting curve date from Ebbinghaus (1885) while mastery learning is probably older than writing though the name dates from 1968 and the earliest unambiguous instance of the concept dates from the 1920s.

https://en.wikipedia.org/wiki/Forgetting_curve

https://en.wikipedia.org/wiki/Mastery_learning