It really all depends on the person. It generally only takes me 20 mins to learn a step, and a couple of hours to perfect the footwork but the personal technique is very ongoing and is always improving and it depends on who i'm dancing with for how in sync we are. If it's the first time I've ever danced with someone, it generally takes a little bit before we get really in sync but there are some people I know that I've danced with them so many times we can practically read each other's mind as to what we're going to happen next.
As for competition, I really wouldn't know but I'd think it would have something to do with how difficult the routien is.
~LB
The question everyone should ask themselves before starting each day: Quo Vatamus