In the classes he mentioned, everyone should be on similar bikes, and be running a similar pace. By "similar", I mean within a few seconds or so. This isn't MotoGP where 0.5 can separate 1st from 15th. Whether they get a perfect flying lap or not, the faster dudes will still be up front. You have to remember we are talking about using the best lap time from an entire practice session, not a 1-off chance at a flying lap. If one lap gets messed up, then try again. If someone is pushing the entire time, making good use of the practice, one of those laps in there will be a flyer (or damn near it).