Unless you get stupid and end up running into each other and generally create chaos in a way you did not intend. You laugh? If you do not put them all in sync is exactly what can happen.
Look at it this way. You do not worry about a collision with a vehicle that is nowhere near you, are those that are close to a potential hazard. Well, when traveling on the road in a group that vehicles are closest to you? His friends more often.
