In my opinion, it depends on why the muscle group is "lagging". If it is genetic, and you are taking roids to "correct" it, then you won't, since all the other muscle groups will in turn grow, which still leaves you with the apprearence that that muscle is lagging. If you have short muscle bellies(short as opposed to long. The difference being easily seen in groups like calves & bis), then there is nothing short of surgery that will enable you to correct it. Sucks, but true.
If by "correcting a lagging bodypart", you meant site-injecting with Steroids, then again in my opinion, there is absolutely ZERO effect, even if you have no genetic limitaions.
If the bodypart is lagging due to simple under-training, then roids are not necessary. Just a better routine. What muscle group are you talking about specificly bro?