Why would marches at the end of a long parade following a band be out of step with marches near the ban?
Marchers march to a drum beat. The drummer usually leads the marchers, so the marchers at the end of the long parade will hear the sound of the drum a little later than the marchers at the front. So there will be a "lag", if you will, in the timing of the steps, as you go from front to the end of the parade. This lag will not be perceptible in a shorter parade.