To add to this you need to take into account the individual muscles - not the movement patterns.

If the right pec is bigger than the left it is very likely that the right shoulder and triceps will be smaller than their counterparts. Because of this even if you do move to single limb (unilateral) movements you are not correcting the imbalance, only strengthening the neuromechanical patterns that lead to this imbalance.

There is a need to ISOLATE the smaller muscles and perform exercises that will not recruit the same neuromechanical pattern as your major mover to ensure the lagging muscles receive the proper stimulus. As these legging muscles catch up the bilateral and unilateral neuromechanical patterns will start to change to utilize the new forces of each muscle resulting in more economical movement.