Two at a time is my rule for going up. When I go down, I can't help but go quickly (unless I'm walking with people). I don't fly down them, but I get sort of a jogging pace going and I kind of 'skip' down one at a time.

Same deal with escalators. Though it's only one at a time going up because of the steeper step. I don't think I ever just stand on an escalator unless I'm using my phone or with other people.