Three. 1 Exa, 1 Edixa, and my Zodiac (Diana clone). I usually do not have more than one camera loaded with B/W but I wanted to do some long exposures and I don't have the proper release cable for the Exa... so I had to load the Edixa. The Zodiac has expired slide film in it which I plan on cross processing.
My F5 has a roll of Portra 400 that has 4 exposures from something, I can't remember what. And one back on my RZ67 has some Delta 50 from 2 years ago that has about 2 shots on it. Again, can't remember whats on it.
I have a small 35mm rangefinder camera in the trunk of each of our two cars. They are both loaded.
All the rest of my cameras are in bags with film at hand, but they aren't currently loaded.
Some times I won't finish a roll, but that is infrequent.
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2
I suppose I have too many cameras, which is why right now I have an old Rolleiflex, Nikon F4, Canon EOS1, and 2 Holgas all loaded with B&W film. Only the Rolleiflex hasn't had any exposures made yet. (just bought a duto filter for it and am trying to figure out what I want to try to photograph) Oh yeah, I forgot an Olympus Epic I keep in the car. I can't remember the last time I didn't have any camera with film in it ready to use. Comes from being a camera junkie, I guess.