I think it's a matter of routines, what you feel comfortable with, "team work". It's pretty much as stupid to do it that way, as not to, what ever floats your boat. I don't do it like that and actually don't need anyone on the line except me and the car, but I have no problem if the opponent need five crew members there. That's his way of doing things and I don't think there really is a right or wrong way.
http://www.youtube.com/watch?v=rBfBNY2Z3N8