Fixed sight handguns are typically sighted in pretty well at the factory, in my experience.
I have done some sight adjustments out past 15 yards to get a gun shooting a little closer to point of aim, but have only very rarely had to mess with fixed sights to get adequate point-of-aim/point-of-impact alignment at 15 yards or closer.
Fixed sighted guns can typically be adjusted for elevation by changing the front or rear sights for higher/lower versions. Usually windage is taken care of by drifting the front or rear sight to adjust. However, again, I've found that's rarely necessary.
If the front post is too tall, once the shooter has found a load or range of loads that work well in the gun, the sight can be slowly filed down until the gun is shooting to point of aim. A too-short front post needs to be built up or replaced.
Adjustable sight guns, in my experience, usually aren't sighted in as carefully. I guess the factory figures that since the sights are easily adjusted the buyer can take care of it after the purchase.