I Like to use the Practice mode for trying out a couple diffrent things (mostly new looks tho), and have thought of a couple minor improvements:
1. Difficulty setting: No Threats
this one is pretty simple, give players the oppertunity to go on practice without having to worry about some sentry's ruining your day!
this way they can easily train diffrent techniques such as Airhug, Reload cancel, or instant walljump without needing a friend or bothering others, even when there are no jump rooms availble.
You can also use it to try and discover new jumps/tricks on your own.
2. Return to Lobby (and/or) Change Loadout
Sometimes you only want to hop ingame for a minute (repeatedly), and dont have friends who are online/want to help you/you dont want to bother them and if you try to hop into practice mode,
and every time you change some part of your Loadout you have to quit and recreate the whole room
I therefor suggest an option to go back to the lobby while in a practice game.
(i think this may be a little harder to implement, but should be possible by bringing you to the resultscreen via losscondition triggred by a button in the escape menu which is only available in practice)
3. Make every map available in practice mode
(pretty self explanitory)
well those are my suggestions/ideas, and im interested to see what you guys think about them