I have seen it done where you play basically with all 4 fingers, one for each fret in a given position up to the 12th fret. For example strating from the 5th position play 5th fret with index, 6th with middle, 7th with ring, and 8th with pinky. And do that from open to 11th fret.
A lot of technique books tend towards this practice cause once you get past the 12th fret your fingers get crammed together and using al four in a given position can get really uncomfortable. I personally have small hands so I taught myself to play with all four fingers past the 12th fret. others use mostly index, middle and ring to handle all the insane stuff up there.
Play wahtever comes natural or you practice the most. No sense in ruining a good thing if it works.