Yes, I have done countless “laps” through the Singing C exercises and felt a greater sense of ease each time.
It takes a long time for our brains (my brains…) to create a new understanding of what to do and when.
I also saw your post on the Practice Routine thread, and I recall we had both posted on another thread about your downstream setting and jaw position, etc.
I recommend seeing if you can Skype with Greg–I imagine that would be the best way for you to ensure your mouthpiece placement is appropriate, of if you need to align things differently / try to play straighter, etc.
I used to play more downstream as well and roll my bottom lip under. Eventually, I would run out of lip as I ascended. It still happens occasionally but I try to play straighter and more forward and centered now and that works better than ever.
It still sometimes surprises me that I am able to play above the staff with such little movement of my lips–it feels, especially when I back off the air, as though my lips just kind of fall into position and it feels more open and forward than I thought possible.