I just finished writing a piece featuring John Jensen on trombone. There is a very personal side to writing for the trombone.  More than most instruments, I find myself writing for the person as much as the instrument.  In orchestral trombone writing I generally stay in the traditional register for tenor trombone.  I rarely go past a G above the staff and I only go there at a fortissimo volume.  In writing jazz/ big band style solos, I really have to think of the player.  In John’s case, he plays a smaller more agile horn than most orchestral guys ( He has that equipment for orchestral gigs)  and his sweet spot is entirely above the staff. in this case I put his “money note” at the C an octave above middle C.  He will nail that. A different player might look at that and shudder.  Hopefully we will get to record this sometime this year.  But I am getting ahead of myself.  We haven’t even rehearsed it yet.