Which Side Of The Rubber Should Pitchers Stand On?

If all things are equal and the pitcher can command the fastball in the zone, then the LHP should pitch on the left side and the RHP should pitch on the right side.  Keeping the arm side closer to the arm-side hitter is certainly advantageous.  However, if the pitcher with sink or run to his arm-side, it would then make sense to switch sides in order to catch more plate.  This change can affect the breaking ball at first, but over time, the pitcher should make adjustments on where to start and finish the breaker.