I keep a half-frame camera in my pack for snapshots and it can take me several months to get 72 photos; sometimes I use 24-exposure rolls to get 48 if I'm feeling impatient. I'm usually surprised when I develop those rolls as they often include photos I'd completely forgotten about.
One time my lab sent me someone else's scan's by mistake and of course I couldn't resist having a look before I deleted them (I notified the lab and they re-sent them to the right person). That roll of 36 was taken over the course of a pregnancy through the infant's first few days, so it took them at least 9 months to finish it (the first photo was of the positive result of a pregnancy test), and I've talked to people who've had the same roll of film in their camera for more than a year.
I watched a documentary about Kirsten Klein, a great photographer from Denmark, who mentions that she's a frugal person so when she finishes a roll of film she puts it on the shelf until she has enough rolls to max out the capacity of her tank. I don't think I could do that; a finished roll of film just fans the flames of my curiosity and I need to develop it right away so I can see the results.