I've noticed it enough times that its beginning to seem more than just coincidence...
1. The first was a friend of mine who studied with Roy Stevens himself back in the early 1970's.
(here: Amazon.com: Embouchure self analysis ; and, The Stevens-Costello triple C embouchure technique: Complete: Roy Stevens: Books)
He had paid considerable money to both take lessons directly from Roy, and buy his book. Then spent the first sixth months or so diligently and methodically practicing. Daily working the book a page at a time exactly as instructed but making little tangible progress. Undaunted though somewhat depressed he continued but took a few days off around the fifth month. Then he picked up his ax on a Sunday afternoon. PRESTO! He was sliding up to and above DHC with good volume tone and decent accuracy. He told me:
"I just loosened up the middle of my chops and blew out these freaking EASY high notes".
2. The next was a personal revelation some ten years back or so. Also on a Sunday and similar to my friend's epiphany. Unlike my friend however I decided to stay with my original chop setting after the discovery for most my work. Keeping the Stevens type setting mostly for demonstration purposes and personal amusement. Although not using the thing much today I still consider it a very rewarding experience.
3. Then just this past Sunday yesterday a young friend of mine called up and explained that through his study of the Stevens book (and some alterations of it that I had prescribed for him) he had "opened the dog gone thing up" and started blowing EASY three and a half octave arpeggios at decent volume and tone. He started with the Stevens thing around the first of this year.
In each case none of them had really made it happen overnight although the change sure seemed that way when it finally arrived. What each had done was set the groundwork in the subsequent months. And while they couldn't be completely certain that the thing would work (both had felt fairly depressed at times while doing it) they still stuck with it.
Analysis: The embouchure change was so radical for each player that it took some 5 to 6 months just for each of them to get grounded in it. To find the spot/connection of the chops "just right" that is. Once the connection became secure? They progressed to amazing and easy register fairly fast. The difficult part was in convincing themselves that they were going to pull it off. Not a lot of positive feedback in the beginning. All were playing unmusical tones for several months at first. Plus the facial and embouchure muscles they were using were undeveloped, and weak. A discouraging feeling especially since all were very capable trumpet players previously albeit with limited range. In my own case I had a solid High F (prior to the experiment) but not a lot more. My old friend has similar range and the kid couldn't play above high D at all.
Number 1 was probably a "ready made customer" for Stevens-Costello. Me? I had to fiddle with the setting a lot. And the kid needed a fair amount of coaching just to find the right coordinates. As the book prescribes he not a good fit for Stevens at all. So I had him work on rolling out his lower lip some.
For the kid and myself what seemed to speed the process up was consistent daily practice of long tones. REALLY L-O-N-G tones that is. Like the "Cat Anderson 20 Minute G". Playing the second line treble clef G for twenty minutes resting and breathing where necessary. In fact for the kid I suggested he lower the G to a Low C and play for five minutes and no more at first. Then gradually extend the tone to ten minutes, then twenty. Later ascend to Low E and then finally to the second line G.
I chose the Anderson 20 minute G (for myself and the kid) not just because Cat recommended it but because the Stevens System is pretty much the way that monster blew. The "right saddle to fit the horse" or something like that. The idea being that in an embouchure that has the latent capacity to blow Triple C's the goal isn't to develop strength so much as coordination. I'm not exactly sure but that seems to be the concept in Jerome Callet's old book "Trumpet Yoga". Correct me if I'm wrong.
"Weakness is strength" Arnold Jacobs once said. He conversely, not being an advocate of embouchure change but the wisdom still just as useful.
So just like the Lotus position in Yoga it seems really strange to hold your chops in such a seemingly weak and difficult position to sustain at first. However after ample time, patience and perseverance the results could be astounding. The main problem being staying optimistic and finding the exacting set of coordinates in the chop positioning and usage required to make the darn thing work in the first place. You won't really know if its gonna work until it does. That can be a drag.
And maybe Sunday does play a part in it too. Just sayin that is...