At 20-24fps, your animation is single framed and you use double framing at places where you think you need to ease.
At 30fps, your animation is double framed and you use triple framing at places where you think you need to ease and single framing to make it look smoother.

i use 24 fps mostly but for some reason the end result is completely double and sometimes even triple framed. I think that it should even really matter(except in collabs) how many fps it is. Your animation should just look good.

24 is probably the most easiest, 30 fps is good for making combos.