Peak Performance is relative. The issue for the beginning diver is control. To some old timers, "peak" means that the diver doesn’t even need it, as many don’t. The diving planet is divided on this issue. However, most diving associations require that when the instructor is "in the act of teaching, leading, or monitoring a dive, while in the water, he/she must wear a BC." Thus, that is not the same thing as to say that all instructor rated divers must always wear a BC when diving. There are a significant number of diving organizations that specifically word it just like that for the reason that there are still people out there diving who believe that "Peak Buoyancy Control Performance" means not having to use a BC at all. Now, that will get most "modern" divers buzzing and snarling, but those "old school" folks feel that sans-BC is a much, much more hydro-dynamic profile, and thus, within the matrix of the whole boiyancy system, is ultimately "Peakerier." Where are they and who still dives like this? Well, they are under a rock, where would you think, lol.