I recently crewed on David Mosely's G-Force 21 along with Tommy Metz; three on board. While reaching we had Tommy on the jib/trap, myself on the main traveler/trap, and David on the Main sheet and rudders. Eventually we figured out that if I worked the traveler and when that wasn't enough, David eased the sheet, and Tommy worked the jib. It was incredible how much attention we could all pay to the job at hand. We slowly figured out who should do what through the 2 hour race and by the end the boat was moving incredibly smoothly for the puffy conditions. We each knew how to perform every job on that boat and still got along great - not easy! I can understand how letting the crew work the mainsheet (upwind; not necessarily reaching where both sails need to be maintained) helps incredibly even on a two person boat.
I've always wondered, while looking at those mono-slugs with 6 people on board, what in the world all those hands are doing! Now I know - we're really overtasked but I like it!