I don't shoot a lot of film- maybe a roll of 36 frames every 4 weeks or so. I continue to do so, primarily because it has a different feel, a different color pallette than I'm used to with digital. I also wait for the right timing. There is also a palpable cost with each frame, so I'm not going to just fire away.
Because I shoot so sparingly, I often wish for smaller rolls of film. 12 would seem about right. I'm also a little spoiled by the resolution and latitude I get with my digital cameras so there's a thought of experimenting with medium format film eventually.
Either way, the types of film I shoot are either hard to get or unavailable in smaller rolls. These were made with Kodak Portra 400, but I set the camera to 200 on the advice of a couple great photographers.