it is less useful for physics, math, and music since fluency is so much important.

It is important for language acquisition too, but the language involves a lot more rote memorization than the above.

>it is less useful for physics, math, and music since fluency is so much important.

I mean, you can put whatever you want on a flashcard. e.g "Derive the fundamental theorem of whatever", "Prove this theorem" etc.

Also music has a extreme level of "stuff you just need to memorise".