I don't know a better way to say it other than "technically contrasting."
My starting point is piano.
Sometimes when practicing piano I want a quick "technically contrasting" key - meaning the fingerings are very different - and so I have a few typical changes I use: transpose up/down a half step, switch from three sharps to three flats, or alternate tonics
Bb to get root and fifth on opposite key colors. That's my quick and dirty substitute for practicing in all keys when I don't have lots of time. By comparison changing between
D major, for example, doesn't provide much "technical contrast", topographically they are nearly the same.
Is there something like this for sax and trumpet? A way to contrast keys for maximum "technical contrast." In terms of fingering maybe there isn't a lot of difference between keys on brass instruments. I just don't know.