I will average about 200-300 rounds a session. Most of that is with my 1911-22. It's set up pretty much identical to some of my other 1911s. The good thing about my 22 is that I run it dirty, and mix up my ammo, so it'll malfunction. The reason for this so I don't know when it'll malfunction, and can practice clearing it, and getting the gun back on target. It's a great thing to be able to get a tight group and all, but I think a lot of people forget to practice clearing malfunctions and getting the gun back to working, quickly.
And lastly, trying to keyhole 22s are much harder than 9mm's or other larger calibers. So it's also a good tool to practice tighter group.
I also mix in shooting my other guns, so I can get the control of my carry guns.