It’s possible to study very specifically for Olympiad math tests. Anecdote: In USA math Olympiad training camp in the early 2000s, I specifically remember that there was this useful technique that required quite a bit of rote memorization to be able to use maximally well (solving geometry problems by treating the points as complex numbers), and only 2 people out of 25ish bothered to memorize the entire sheet of formulas. I wasn’t one of them … It seemed unpleasant, I was a teen, I didn’t care that much.
If South Koreans etc. study N hours motivated by whatever, then I can easily imagine that North Koreans study 100*N hours motivated by life-and-death consequences for them and their families, and having no other classes etc. for years on end, or whatever it is. That could make a big difference.
It’s possible to study very specifically for Olympiad math tests. Anecdote: In USA math Olympiad training camp in the early 2000s, I specifically remember that there was this useful technique that required quite a bit of rote memorization to be able to use maximally well (solving geometry problems by treating the points as complex numbers), and only 2 people out of 25ish bothered to memorize the entire sheet of formulas. I wasn’t one of them … It seemed unpleasant, I was a teen, I didn’t care that much.
If South Koreans etc. study N hours motivated by whatever, then I can easily imagine that North Koreans study 100*N hours motivated by life-and-death consequences for them and their families, and having no other classes etc. for years on end, or whatever it is. That could make a big difference.