I'm a euphonium performance and music education double major, and my college audition is on the 25th. This audition determines my seating in most of the ensembles I'll be performing in, and while the order is fluid, it's relatively important to me that I do well on this audition.

However, I've been working full-time at my job, helping out with a local marching band, and have been trying to find a way to get my schooling paid for. Not a lot of time to be spent practicing - and it's showing in my audition music. Sure, I can get through it, but there are several sections that just need work, and I feel that I don't have the time to dedicate to them. Even on days where I have the time, I'm usually so drained that I can barely bring myself to pick up the instrument - today, I worked 7:30 AM to 9:30 PM. Nice pay, but it's truly all I can do to buzz a little and play a few long tones.

What're some practice methods to get the most out of the time I have, and what exercises can I do to help maintain my chops during spells where I have little time to practice and play? I've been working on my music measure-by-measure - taking it slow, deconstructing it, and slowly adding it back together. It works, but is tedious, and I truly worry there's no way I'm going to get all my audition music scanned through in time for my audition. I've also been doing quarter tempo until I can play it 5 times in a row correctly, then half tempo, and then 3/4 tempo, and then full tempo. That helps with certain fingering/slurring issues, but again, takes quite a bit of time. I tend to buzz quite a bit in general - on my 30 minute commute to work, I buzz in the car, usually just to whatever I'm listening to. If I'm laying around watching TV after work, I might buzz a bit every 10-15 minutes to keep myself engaged in the show. But my time on the horn is limited - especially on days like today, where even if I have the energy to practice before or after work, there are people sleeping basically every chance I get.

I know there's no magical tricks and that it's going to take work and sacrifice no matter what I do, but what would you guys do to get the music in the best shape possible in a week? Can you offer some buzzing exercises, some playing ones, and maybe some practice techniques to deal with particular issues (slurring patterns, articulation patterns, etc.)? I'd appreciate it!

My music is as follows:
Fantasia Di Concerto, E. Boccalari (1:25 to 2:50 on this recording - https://www.youtube.com/watch?v=gJRVviuCuX4)
Fingal's Cave Overture, Mendelssohn (beginning to about 1:00 - https://www.youtube.com/watch?v=zcogD-hHEYs&t=54s)
Finale from Tchaikovsky 4 (beginning to about 0:12 - https://www.youtube.com/watch?v=A0nlu_cBuJQ)
Festival Variations, Claude T. Smith (about 1:23 to 1:50 - https://www.youtube.com/watch?v=ZdmbC_A-Www)

Thanks! Any recommendations at all are welcome.