[summarite]

It is taken up, just not everywhere and not necessarily at scale. I've personally seen it used eg at Finnish schools - but there the teacher chooses the tool, not the government, so i don't know how common it is.

With more and more devices in class you can expect directed spaced repetition to hit hard. But actually i don't know a single person who didn't at some point get the instruction/advice to use flashcards for foreign language vocabulary. That being said it's not used much in other subjects - because no serious educationalist thinks education is about hammering facts into the brain. It's much more about concepts and critical thinking, at least in any semi-modern classroom .