The measure of whether a sight adjustment is needed (with ANY gun) should be the group size. If a person is executing the fundamentals of shooting in a sound and consistent manner, then the group of shot holes should be very tightly clustered on target, and the need for a sight adjustment should be apparent (as in your case).

If, on the other hand, the group is scattered/excessively large, missing shots altogether, or trailing-off in a comma shape, then proper applications of the fundamentals is lacking, and a sight adjustment is just as likely to move some shots away from the target center as toward it. This is one of the reasons that I've never liked that "group analysis target" that I see floating around the Internet; it does not take into account the size of the group, and automatically assumes that the shooter is doing something wrong based on a general area of the shot impacts. In your case, it would have been completely misleading, and could have cost you time and ammo money chasing a problem that did not exist.

I have NEVER seen a new-ish shooter who could slap/jerk shots consistently into a tight group. Same thing with poor sight alignment/picture, follow-through, grip problems, etc. The size of the group on target will tell the tale.

"If the group is tight, fix the sights. If the group is scattered, the shooter is the matter."

I do the same thing, but I do it with ALL of my guns. I consistently shoot very slightly to the left. In my case it has to do with my hold on the gun. I know what I'm doing "wrong" and I've been doing the same thing for more than 30yrs. It is easier to slightly adjust my sights than to retrain three decades of constant shooting. I also ONLY shoot that way 2 handed. If, for some reason, I shoot one handed I have to aim slightly right to compensate for my sights being adjusted. My "bad habit" is that I slightly retard my support hand. The heel of my left hand is rotated slightly too low, resulting in the tip of my left thumb being behind my trigger finger instead of the tips lining up properly. I've ALWAYS done it that way (broken wrist when I was 6, it's a bit crooked). If you are consistent, adjust the sights. If yer all over the map, changing the sights won't help.

John