Some time ago I switched from 36 exposure rolls of 35mm film to 24 exposure rolls. I was holding the two ends of the film when it came out of the developing tank and snapping the film, rather than wiping it, to remove excess water. The 36 exposure rolls were right at the limit of my reach. I would occasionally lose my grip on one end and let it drop to the floor. Not a good thing. Switching to 24 exposure rolls solved that problem.
I hoped it would help with another problem too. I would frequently choose a film and ISO setting for the light meter for a particular event or place, take those pictures, and then find myself with half the roll or more unexposed. It bothered me to remove and develop a half exposed roll, so the film would remain in the camera until I was ready to take more pictures when, more often than not, the film and selected ISO were not what I would have preferred. And I found this happening just about as often with 24 exposure rolls.
Last year, for unrelated reasons, I started bulk loading 35mm film (I’ll post more about this later.) and decided to try even shorter rolls. I didn’t remember having any difficulty finishing a roll of film when I was taking 12 exposures on a roll with a Rolleiflex, so I loaded 12 exposures of HP5 Plus in a FILCA cassette (More about these later too.) and went to the beach to see how the sand replenishment was proceeding. I came home with 10 frames exposed and took the film out of the camera without hesitation. Success! 12 exposures is now my standard load.
If I always exposed every frame of every roll of film these 12 exposure rolls would be wasteful. The unexposed head and tail of a 12 exposure roll are the same length as those for a 24 or 36 exposure roll. But given the number of unexposed frames or junk finish-the-roll shots on most of my previous longer rolls I think I might actually be money ahead.