Old timey three finger style?

Описание: I've been messing around with 2finger thumb lead. but on some tunes it just comes
natural to pick the first string with my middle finger. so i end up doing part 2finger and part 3 finger. i'im also sounding 2nd and 1st strings together with index and middle.
I wonder if this is a "proper" way to play an old-timey three finger style? i'm just playing
what seems to come natural.