By increasing the pool of muscle fibers capable of contributing to the pedaling action, you increase the amount of rest opportunity for each so you can sustain a given speed longer before motor units begin to fatigue. 12 Weeks to Stronger Cycling
It was 1999 when Mavic debuted their wireless shifting system. When it did work it was found to be too slow in race conditions. It just couldn't change gears fast enough. Cycling team Swiss Post had it on their bikes for a while.