Exactly. A better thing for guys with a big imbalance between one side of the body and the other is to work the weaker side first to failure on unilateral exercises and do no more reps or weight with the stronger side, even though they won't be failing with the latter. This will allow the smaller side to catch up, although they will never be equal. Doing stuff with things like barbells will make the stronger side to do more work, especially closer to failure.
exactly what i was going to write.
may i add....generally if you have one arm larger/stronger than the other (due to dominance or whatever), then when doing compound exercise such as bench or pulldowns etc...the opposite prime mover does more work to correct the overall strength in that movement.
i.e. if your left tri is stronger than your right, then your right pec is larger than your left... or if your right bi is strongest, then your left lat is stronger/larger..and so on.
throw in the delt in there and theres all kinds of mixes. it would be unusual to have larger muscles on just one side only though...