If by 'over-feeding' you mean keeping the fish well fed, then, yes, it is a worthwhile goal regardless of the specific reason. A healthy fish population (not just feeding, but space, tank-mates, etc.) will be better able to withstand disease; things like fin rot, lympho, HLLE, etc. Whether healthy fish are better able to resist a parasite like ich is less clear. My experience is that an aggressive strain of ich will burrow into a healthy fish just as effectively as it will into a less healthy fish.