Trumpeters have a tendency to fixate on their range. They're either proud because they can play higher than anyone they know, or they are frustrated because they can't play as high as they want. During my comeback, I've been rather guilty of the latter case.
For the first few months of my comeback, I could barely play anything at or above an E at the top of the staff. It has been a frustrating journey, but I've now got a (somewhat) solid range that extends up to a Bb above the staff. I can play higher than that occasionally, but I can't play those notes with enough power or consistency for them to be truly useable.
A Bb above the staff gives me about two and a half octaves to work with. That's enough notes to play most of the solos by Miles Davis, Kenny Dorham, Art Farmer, Blue Mitchell, Chet Baker, and many other great jazz trumpeters. I think it's safe to say I should stop worry about my range.
While my range is fine, my *real* problem lies with endurance. On a typical day, I've only got 15-20 minutes of solid playing in me, before I need to rest. Once fatigued, I can barely play an E at the top of the staff, and I have to use excessive pressure just to do that. Playing beyond 40 minutes in a single session (even with short breaks) is out of the question. At best, I can manage three or four 20-30 minute sessions throughout the day --usually two in the morning and one or two at night.
Since I'm still in the process of strengthening my chops, I have to devote a couple of these short sessions to fundamentals (slurs, articulation, etc). That leaves just one or two (at the most) short sessions for improvisation. This limitation is especially discouraging when you think about the great jazzers who honed their skills in marathon jam sessions and constant woodshedding. I'm already at a disadvantage talent-wise; I'd love to try and make up for that with extended weekend practice sessions, but my lack of endurance just won't let me.
SEARCHING FOR SOLUTIONS
I've been working on the Balanced Embouchure exercises for a couple of years now. The author claims that his method works for everyone. Well, either I'm doing it wrong, or I've got a good "truth in advertising" case against him! --just kidding. The author is a nice guy, and had graciously tried to help me when I was beginning BE. Regardless, I just don't think the Balanced Embouchure method is working out for me.
I've been working on Caruso and Flexus exercises for nearly a year now, and while I do think they have helped my overall playing and strengthened my range, I've yet to notice major improvements in endurance. The way I see it, I can continue with what I'm doing and hope that my endurance improves over time, and/or I can try something new. 2021 Update: As I'd learn in my lessons Nadje Noordhuis, I wasn't doing the Caruso and Flexus "6-note" exercises correctly... so no wonder they didn't help as much as I had hoped.
A visitor to this site (thanks, Peter!) recently suggested that I try superchops. I've also read quite a few posts about it at the Trumpet Herald. I do have some reservations; mostly revolving around the fact that I can't roll my tongue and therefore might not have the necessary flexibility to pull it off, but I must admit that I'm tempted to give it a try.