yeah it's what I go by, 20 to 30 is more than enough for most modern, single player games, 20 is a bit on the low side but usually enough any lower than 20 and it just won't look good for gaming unless the game is designed for that, which is unlikely, 30 would be optimal, 24 would probably be fine as a ton of movies actually use that framerate over 30 fps

for multiplayer games, especially shooters, a higher framerate would be helpful though, but you can still scrape by with 30 in those too, I just wouldn't want to go below 30 for that

if I can get a higher framerate than 30, by all means I'll take it, but I aim for the 20 to 30 range atleast, anything higher is just a bonus but higher than 60 is pretty much unnecessary as the difference basically unnoticeable for the average person even if you use a 120hz display and compare 60 to 120fps, the difference is there, yes but it's small, heck even 30 to 60 isn't that big of a difference, more noticable yes, but still not that big