If military is in a movie or TV show, there’s usually an establishing shot of the post. It shows various buildings and soldiers running past, calling cadence.
Fact or fiction?
A cadence is a work song sung by the military when they are either running or marching. They’re also meant to keep the soldiers moving in step. From what I understand, the Marine Corps even has a school that non-commissioned officers attend to learn how to call cadence. The Army doesn’t have any such school, so sometimes the results are pretty awful, since not everyone can sing!
The fiction part of what Hollywood shows is that usually the main characters is time of day, as if soldiers out running could happen at any time of the day. Physical training is always first thing in the morning. We had PT formation at 6:30 and were done by 7:30. That was a firm schedule.
Probably one of the reasons no one did it later was because we ran on the streets, and if everyone was doing PT at the same time, there were fewer cars to compete with us. During the morning, you could hear the cadences being called everywhere as the units all went out for their runs.
BTW, even our local fire department does cadence. I’ve sometimes seen them out running–on the sidewalk (couldn’t run on the streets in our area. Too many cars). Early in the morning.