My thoughts are: If it's the gun that you carry everyday for personal protection, you may not want to have to think "Ok, I'm carrying XYZ today so I have to hold over/under XX at 15 yds". You want to be able to defend yourself without having to think, just pure reaction, put the sights for center body mass (or whatever you want) and pull the trigger. You can tailor what is in the gun, be it reloads or factory loads to have POI=POA at whatever yardage you want or practice with your carry ammo to see where it impacts and adjust your sighting as needed or have a standard load and file the front sight. Myself, I would limit it to 15 yds. If the bad guy is farther away than that and you shoot him, a DA may say, "why didn't you just run away?". Next it depends on what load you are carrying. If it's a reload, you can pretty much duplicate that load over any number of years so your POI is always the same. If it's factory ammo, will you be able to get that same exact load 1, 2, 5, 10 years down the road. If you can't then you have to research different ammo to get the same POI you had before, or do more sight work. And if your new load shoots high, you'll have to either try to build up the front sight or buy/install a new sight and file it down.
Myself, I have several guns that I might carry on any particular day or situation. I practice with them using a B-27 target (sort of a body shape) I aim at center body mass at 7 and 15 yds and see where the gun is shooting with the sights aligned. I them just remember where they are shooting and adjust as necessary to move the POI. That said, I have shot PPC and some other police type competitions in the past and that gets you in the mindset to know exactly what to do (sighting wise) in certain situations. Probably the biggest thing is to practice, practice, practice. I run across too many people that think, "Well I shot 50 rounds through my personal defense gun so I know I'm good to go." No they're not, you have to practice regularly, and at different distances, in different lighting if you really want to be able to defend yourself. I can tell you that here in PA, in the winter, when it's cold, very few people that profess that they are ready, go out in the cold to practice. They have no idea how things change when they are wearing heavy clothes, gloves, etc. Then there are the police. Police are a good bad example. Most do not practice regularly and it shows when they get into gun fights, read the articles like "Police fire 57 shots at bad guy and hit him 4 times - and the distance probably was under 50 feet.
I guess I would say, and this is just my opinion, is that if you have one self defense gun to use, prep it so that you can use it under any condition, without thinking about what you have to do. If you have more than one gun, practice with them all so you know what you have to do, with minimal thinking.
