Maybe some MGE but that's because I like playing it.
I'll play some public, then 10 minutes before a game I put a sticky on the floor/wall and jump around it trying to track it.
I do that mainly because I find it really helps me to get focused 100% as I think about what I need to do/remember for the game. So I don't think I really need to practice a whole lot anymore.
For demo it's hard to really practice, DM servers and MGE don't really offer much so I'll just go over maps again and again, finding and testing traps, learning spam arcs etc.
I should really be practicing rollouts though.