Hey TM- I'm an upcoming senior in high school and have been rigorously working range to get comfortable
with a demanding marching band piece (open pedal C to 3rd C chromatically and by way of C arpeggio)
I've noticed that toward the end of a day of 20 play/20 rest practice sessions (totally playing time usually around 3 hours)
my control is shot- I feel somewhat of a slip or shift so to speak right around 3rd A. The rest of the ascension up to 3rd C goes fine...
but on the way down my embouchure fights to stay up up UP. I've tried to first counteract this with modulating the airstream, then even went as far
as to attempt some form of counter pivot/shift. Thus far, nothing has worked. The next day, everything is great!...until around 1.5 hours. (this wouldn't be an issue
if I didn't need the ridiculous endurance it takes for marching band -_-)
'37 Stradivarius 2011