Noisy bastards! Some of us learned silence is golden - because we can hear you lot coming a hundred miles away, and that gives us plenty of time to prepare the welcome party...
As a drill or route march practice, this chanting harms the sense of listening to what your platoon is doing. That sense is essential in combat, because that tuning keeps you clued up to them.
As far as the slow march is concerned, the technique us Brits used to use is to teach it as a step and a stop. You place your front foot and bring the other up to it, outside of the foot going down first, change balance, step with the other and bring the first up to it, change balance...