That's sounds like a really promising insight. Since the urge to breathe is triggered primarily by changes in blood pH etc (as opposed to absolute levels), your idea seems like it could actually cause the urge to breathe to decline for a long time into the hold because receptors would be subject to a constant or slowly falling pH level.
It also helps explain why sudden hypering seems to make breath-holds initially very comfortable and then you suddenly hit a wall in a relatively short time (at least I do).
In fact, it explains a lot ... I'm going to try putting this idea into practice (sans 6:30 statics
).
