I always enjoy your tips based on your past experience as a trainer. This is how I've had this taught in a couple different defensive pistol courses that were taught by local LEO's. I'm guessing it's how they were taught it.
Out to 3 arm lengths (8 to 10 feet or so), you're shooting from some type of retention, so that's instinctive pointing.
From 3 arm lengths out to a couple car lengths (maybe 8 feet to 20 to 25 feet), you're not using the sights, but indexing on the back plate of the pistol slide for your aim.
Past a couple car lengths, you're acquiring the sights on the pistol.
Based on your experience, what's your thought on that approach? How would you teach use of sights now?
Basically, you're describing what's often called
indexed/point, flash sight and sighted fire.
Don't forget that it also depends on the size of the intended target area into which you need to make the hits. Then, there's also the potential for the relative motion of both yourself and the threat at the time to take into consideration. I remember some years ago when one major agency had a study done in which it was observed that in almost 64% of their OIS incidents both the officers and their attackers were in motion.
The cranial vault is a very small area, and it might be moving. Sighted (aimed) fire might be critical in order to get the hit(s), even at closer distances.
I've watched some shooters during a more difficult qual scenario miss many, or even all, of their shots on an initial run through it. The scenario required them to move diagonally while advancing toward and across a threat target's position, while firing to obtain several accurate hits. No "cover" was available. The distance from the shooter to the threat target started at approx 9yds and could be as close as approx 4yds, depending on the path used and the shooter's movement. The number of rounds that could be used were limited to a max of the shooter's primary magazine load (which varied from 12-15rds, depending on the weapon). The shooter had to manage recoil and still obtain accurate hits in the short time allotted to traverse the distance. COM hits were encouraged, as was using 2-handed shooting, and the timing/pace of the shots fired were up to the shooter.
Many folks surprised themselves by how well they were able to apply the skills they'd acquired and had been using in other qual/drill scenarios over time, bringing them together.
I remember guy missing with all of his shots, though, and being surprised when I showed him the target. In disbelief he asked me how he could've missed all of his shots. I told him I didn't know, but that whatever he'd been doing, he'd made it look pretty easy. Listening to him, it seemed he thought he'd been pointing the gun, 2-handed, and "shooting instinctively". Well, "instinct" can still be "off".
Then I suggested we try it again, and this time he use either a flash sight picture or aimed/sighted fire, taking whatever fractions of a second he needed in order to accurately put his hits where he wanted them to go, with & between each step he needed to make. His timing on the next run was very close to his first run, but he didn't miss a single hit and he actually looked smoother in his movements. He felt more confident about it afterward, too. (One of the whole points to successful completion of all scenarios and drills was for the shooter to have the demonstrated confidence to know that he/she could DO it again if they needed to, for real, upon leaving the range.)
Don't assume and hope.
Put them where you want them to go. Aimed fire, whether "flash" or sighted (using front & rear), can help toward that goal.