I'm exclusively a Glock shooter. In fact, I don't think I've shot more than 100 rounds out of any other kind of gun in the last two years or so. I have owned other handguns in a silly quest to find the "perfect" handgun but always came back to Glock perfection
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As long as I've owned and shot Glocks, I've drifted the rear sights to compensate for shooting left. I drifted them significantly.
I've advised other people that it's OK to do the same to their Glocks. It seems like every other week here in the Glock forum we have someone asking how to fix their Glock hitting left. If you pore through the archives, you'll probably find dozens of my comments to the effect of "if your hits are repeatable, it's fine to drift the sights".
Over the last year, as my practice and round counts have increased (approximately 20K live rounds since this time last year/ easily 500K dryfire reps), I noticed a funny thing. I kept hitting right. I would adjust sights ever so slightly to the left and carry on for a few months until I'd have to do the same thing again. I've done it three times in the past year.
Yesterday I went out for a short live fire session and discovered I was hitting right (again). I got the sight pusher and adjusted to get my POI correct and discovered that the rear sight was perfectly centered on the slide.
As my trigger control has improved, the distance of sight drift required has shrunk to zero.
I still think the axiom holds true: "if it's repeatable, it's fine to drift the sights". But the corollary seems to be that as your skills increase with respect to trigger control, you will find you require less and less rightward sight bias.