Knowing that I should not step into this discussion, I will anyway.
Jack Kanstul makes the statement:
"The fact that it is a "systematic approach" using many worthwhile books
from other teachers allows anyone, if they follow it's instructions
carefully, to develop into a well rounded player."
This type of blanket assertion really bugs me - sorry Jack, I think you are a great guy, I just disagree with this statement. The Claude Gordon method works quite well for some players. For others, it doesn't. I would assume this is because we are all different. In education, there are multiple methods for all instructional goals. One of the jobs of an educator is finding the right method for the pupil. I have a learning disabled son who is extremely bright, but he can only learn through certain methods. As parents we have to find the right method to teach him things, and we have to make sure his teachers do, too. One method does not fit all. What works for our other kids, does not work with Nathan.
Going back to trumpet instruction, I spent three years (my high school years) working with two different Claude Gordon method proponents and had a few lessons with Claude. I practiced diligently, several hours per day. Never got anywhere. During that time I went from being at the top of the heap to the bottom, as far as my peers go.
Fast forward 15 years when I hook up with a teacher that advocated methods contrary to Claude Gordon. Two pieces of advice that I had received from my lessons with Claude Gordon that had stuck with me through the years were to run from an instructor who advocated mouthpiece buzzing, and to not change my embouchure. The teacher I hooked up with who turned around my playing changed my embouchure, and has me doing 10-15 minutes of mouthpiece buzzing each day. I was skeptical, but was willing to give it an honest try. This change was 5 years ago, and my improvement has been dramatic and continues. Another thing that my teacher had me do (or not do) was to stop playing pedal tones. Zero, zilch, no pedal tones. While my upper range sucked, pretty much ended at the top of the staff, I had a good, solid, double pedal C. After playing pedal tones for 20 years, I was leery about stopping, but great progress has been made. I've add an octave to my range (when the chops are fresh I can squeak pass the mythical dubba C, at the end of a quintet rehearsal yesterday, I had a comfortable high g), but have no idea what my pedal range is.
So, I consider myself to be a case for Claude Gordon's method not working for everyone that follows it. I'm not saying that the method is wrong, or bad, just that it, like any other method, does not work for everyone. There are other methods that work well for other types of players. I think what sets me off on this is the implicit conclusion from Jack's statement that if someone fails to develop as a player when following Claude Gordon's method, it is the fault of the player not doing things rights. In my opinion, it is the fault of the educator, not matching the appropriate method to the pupil. I spent years believing that since I could not succeed following Claude Gordon's method, I was missing some unidentified "gift" that would allow me to be a trumpet player. I often wonder what I could have accomplished with the trumpet if I had realized that it was the method not the player when I was 16 instead of 32.
I seem to recall going off on a similar diatribe in response to John Mohan a few years back on this same subject. Guess I'm just a bit defensive still. And interestingly, the teacher who turned around my playing was Gerald Webster - Dwight Bird's mention of him is what set off this rambling.