I had a roll of HP5 that was in my Nikon F4 since last summer. I only put about 6 shots through it. The cool think about film is that you can just note how many frames you've shot, roll the film up and put it in another camera. Pretty tight. Which is exactly what I did. I put it in my M7 and continued shooting. That's of course after I shot 6 blanks to make up for the 6 frames from the F4.
Anyways, I also pushed the film two stops from ISO 400 to ISO 1600. That's probably gibberish to you, but if you're really curious, Google it! It's pretty cool. I've recently just started to push my film. This is the second roll I've ever pushed.
This was more of a test roll, so I tried to shoot whatever I could lol.