Units that stand still should not have any effect on movement. Movement becomes more demanding when near complex pathing patterns so the duration that a mini-move will last is shortened.
You can have 200 units per player moving if they have no collision and are in an open field but you will only be able to have a dozen or so moving with collision in a complex pathing environment.
I found out about it with a combination of knowing common game mechanics and observing what happens.