Is it possible for you to suspend practicing for several days -- or a week? Like a vacation? I find that when I do this (generally a matter of scheduling rather than practice strategy or addressing a problem), I feel surprisingly good when I start playing again, and things tend to work quite well. I what you're doing starts to feel like a grind -- and if you aren't a professional who has to practice so much -- try just taking a break.
Gary Merrill
Wessex EEb Bass tuba (DW 3XL or 2XL)
Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
Amati Oval Euph (DE 104, Euph J, J6 euph)
1924 Buescher 3-valve Eb tuba (with std US receiver), Kelly 25
Schiller American Heritage 7B clone bass trombone (DE LB K/K10/112/14 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)