i have never found this 'skipping technique' to stop a bike faster than a simple skid... i dont see how it could. in my experience, the fastest way to stop on a fixie (without crashing, of coarse) is to skid with as much weight as possible on the rear wheel -- either completely seated or your ass a few inches off the seat. it takes a much stronger pull than i usually would want to make, but it works if you have to stop fast (assumoing you dont have a front brake).