http://www.bitquabit.com/2007/02/14/smart-guys-date-in-parallel/
Because we’re dating in parallel, we compensate automatically for higher resistance. Even though Lisa clearly is just not putting out, the result isn’t the massive slow-down we saw before, but instead results in conservation of energy, as you expend less effort on a mostly dead branch and focus instead on more promising branches. Whereas before, Lisa sucked the majority of our energy, now Sally and Judy do—at 16.2 and 9 jewels, respectively.