Well I don't do anything intricate but I prefer picks that have worn a little to brand new ones and tend to keep them for months. My own preference is a Gibson heavy black triange or similar.
The heaviest user of flat picks I knew was a bass player (and a very good one). He would sometimes join in with some of us in a sort of pub bash/session with an accoustic bass guitar. I've known him wear out say about 1/3 of the material on 3 or more of the same Gibson pick I use during the course of an evening in his efforts to get as much volume as he could out of the instrument.