I am ok with example you cited... but even in that case i would prefer they come back to their battle line formation if and when they come to halt in normal/passable ground.
And even in grassy plains - i deploy them in a formation and aske the whole army to advance. There are no visual hinderances in the terrain. i have seen them change formation. i have to redeploy them to get the same battle line.

It probably would help if we are not allowed to drag in unpoisitionable areas... this is most problematic inside the city/castle.