[stan_rogers]

It wouldn't be about "not learning how to count", but about keeping a rhythm that makes the time predictable within a relatively small variation. I used similar tricks for long exposure photography back in the long ago. (There was a period in the late '70s and early '80s when radium illuminated dials had gone away, their replacements didn't stay illuminated long enough, GraLab-type timers were too bulky by far, and neither LEDs/micro fluorescent segment displays nor LCD side-lighting on watches were up to the task. I had, between cadets and the regular force, more than a decade of military experience then. British Grenadiers - a marching tune - takes 16 seconds to play/whistle/hum through once, breaks down easily into 4-second chunks, and only "feels" right if the speed is right for a 120 paces-per-minute march. Heart Of Oak takes 32 seconds, etc. That allowed me to be remarkably consistent across exposures without a usable external timing device. Habitual prayers, especially when combined with something like a rosary to keep the count accurate, would have the same sort of consistency.)