Seems to be a special U.S. Army institution; never heard it in other armies.
In the German army the drill sarge calls a cadence of 8 paces with: "Links - links - links, zwei, drei, vier" [left - left - left, two, three, four] to break the rookies into one.
Afterwards a song may be used to keep cadence; so every platoon in my boot camp had a favourite song it could be identified with at a greater distance.

Greetings to all swinging servicemen!

Wilfried