Stick Time: The Marching Choir

A choir singing as it enters can be a very cool effect. Or it can be a train wreck.  The challenges are many. Singers tend to rush anyway, and marching seems to exacerbate the problem.  Hearing the rest of the choir is also a problem while moving, both because a straight line isn’t a normal choral formation and the acoustic properties of a room change as one moves from one place to another.  BUT it can be done successfully both with good effect and solid musicality.  What does this choir do in that moving formation that helps them succeed?