I began photography in 1973 and do not remember ever seeing a 12 exposure rolls of 35mm film. But I have learned from this thread that they did exist at least for some time in some places. I think 126 cartridges were 12 exposure.
I do remember the 12 exp 35mm rolls, although I could not imagine them being useful as a standard item. I am almost sure that the place I worked did have some at least in Kodacolor. I was more into trying to get the customer to shootthe biggest rolls we had to fit their camera, explaining the cost for picture would be lower, and never mentioning that I know that folks will Kids would shoot a 36 exposure roll as often as they would use a 24 exposure roll, but did not feel guilty as I imagined that they would appreciate having more shots of their kids.
I understand that there was a special "Police Identification" film of about 5 or 6 exposures. Only sold to Law enforcement, who had to track the film in processing to be able to swear in court that the pictures that were shown in court were the exact pictures that they took at the crime scene. they probably had to go directly to the place that processed the film and stare at the machine until the film popped out, and they checked the twin-check themselves. I also recall hearing about the short Real-estate rolls although again I never saw one in person.
110, 126 originally came in 12 or 20 exposure rolls. at the time 135 was in 20 or 36 shot rolls. The 20 exposure rolls on all three became 24. I vidily recall having to reassure at least one 126 customer that the NEW 24 exposure roll would indeed work in their existing 126 Camera, "the cartridge is the same size, there is just a bit more film inside"
I have heard that the early Kodachrome came in an 18 exposure roll.
UP until the Flash Bar, flash bulbs came in 12 shot packages. 12 bulbs or 3 cubes. even the M3 bulbs came in 12 packs.... (exception was the RED based flash cubes- for Polaroid, which came two in a package.) Flash Bar for the polaroid was 5 shots a side. Flip Flash started at 4 bulbs per end, but I also have seen some with 5 bulbs per end. arround tha time, electronic flash came to dominate.
european flash bulbs I don't recall seeing, (PF2 and so on) so I am not sure if they came in 10 or 12 shot packs.