I was wondering what everyone else does when you are limited and just have to get in some time on the horn.
I do diatonic arpeggios down to pedal C, then some diatonic scales and slurs .. the Arban tonguing interval exercises (the one everyone does)
The 16th note tonguing exercises.. diatonic again up to high C
Lip slurs starting below the staff and moving systematically up to G
Range exercises .. argeggios
Cool down to pedals
it probably is more than 30 minutes but that's the jist