Hi Brad to add to this conversation review these short videos by Jim Manley where he mentions asking Maynard about his breathing. However I can only assume that Maynard was super efficient to play the way he did.
Part 1 https://www.youtube.com/watch?v=NN1FLJUZ53o and Part 2 https://www.youtube.com/watch?v=-At_upbYTRA.

It wasn’t till I watched the Arrrrticulation Four Rs video that I have begun to understand what Jim was on about with his explanation of breathing and embouchure and his crazy range. I have watched Jim Manley’s videos a lot but have only be able to start putting the pieces together since watching Windwork videos and following the process.

Cheers

Ryan