I discussed patterning at my club not long ago. The other shooters were all SERIOUS shooters of skeet, trap and sporting clays. None had ever patterned their guns. I pattern all of mine with the loads I intend to use. I have found a few that were off a bit and one that was off a lot. I've not had a problem with light loads but you never know. I'm not too serious since I'll shoot a tightly choked gun at skeet because I just feel like shooting that gun that day. I'm very surprised that these serious shooters who own expensive target guns with expensive chokes screwed in the barrels never test their patterns.