Please consider that film advance on 120 cameras is much different than on 35mm cameras. In 35mm the sprockets are engaged and after so many perfs pass the film advance stops. Very easy to movement and measurement to replicate. In Rollei's the film advance metering is done by detecting the take up diameter increase not the amount of film that passes the film gate. The required advance, based on the roll diameter increase is approximated by the camera's mechanism. As long as there is no image overlap and the 12 exposures all fit on the 32.5-inches of film the camera's operation should be considered fully satisfactory. Even spacing is not a requirement that even new cameras could provide.