I've been collecting trumpet books obsessively and I have most of "the" ones, still missing Claude Gordon's Systematic Approach .... and .... Deep Breathing, and I need a Clarke's Characteristic Studies (but have two Technical Studies lol) and this exercise in various forms just seems to be "around". Wasn't Gordon also in favor of, holding the last note until you're just OUT of air? That IS like doing a crunch. The 7 in 7 thing is great though, my range is going UP.