In spending over 25 years as an Instructor, mostly training new to firearms men and woman. In Toronto Canada. You have to teach a technique that will be able to be instantly available, in a self-defence application.

At the start of my training (1980), everybody was carrying Smith & Wesson revolvers.
Whether they were 38 Special or chambered for .357 Magnum cartridges, only 38 special ammunition was allowed.

In studying shootings both in Canada and the USA (our next door neighbours) both with Security Officers, and LEO. It soon became apparent, that there was very little chance of a Security employee armed with a Revolver, was very likely to ever fire his, or her revolver, in Canada other than on the range.

So my focus was on teaching a simple system, that would be retained.

As the revolver was carried in a holster always, all training had to start from the holster, and only 6 rounds were available, so not to waste the rounds was very important.
And any reloads had to be from speed loaders, in pouches on the belt. Swing out cylinder, point barrel at the roof, smack ejector rod invert, speed load, back to aim, freeze for an instant, and holster.

As a revolver was instantly ready to fire, double action, just by pressing the trigger all training was in double action mode. This same method of firing the revolver could be duplicated, with no rounds in the cylinder, as in dry fire, much invaluable training could be done that way.

In training Police Officers, I soon found that improper use of sights, had rounds striking low on man-sized cardboard targets, as close as 7m even though they had good groups. Trigger control was good, aim not so much.

I had one of my training revolvers, spit lead, badly from a miss aligned cylinder.
With the cost of S&W fixing this problem almost at the cost of replacing it?
I threw the cylinder away, and the latch that swung it out. You could now press the trigger, as in firing mode, but never able to load rounds.

Find the master eye, show the proper grip, individually! My classes were 8 at a time, as the indoor range could only safely hold 4 students at a time, 4 to shoot, 4 to pick up brass, and load speed loaders.

Hold the cylinder less revolver in the proper combat two hand grip. Have the shooter aim at a target. I would then stand in front of this none firing item, use my eye, to look at the shooter's master eye, manipulate the rear sight, so as to align up our eyes, then bring up the front sight to fit in the rear sight notch.

Quite the revelation to the Cops who had been looking over the sights for twenty years! Instant point of aim, point of hits.

New Security Officers ingrained correct use of sights. All draw and fire exercises, double tap. After dropping revolver to the ready position, the next command would be fire again, or holster.

Requal each year, fire around 100 rounds of my re-loads, in various exercises, then use the carried for a year company 18 rounds, to shoot the twenty round test (I know, I gave each Security Officer two rounds!) after cleaning their weapons, new rounds would be issued (Small companies brought their own) My one big company over 400 hundred of a staff, gave me a case of 38 +P to issue 18 rounds to the newly qualified Officer.

I could go on for ten more pages (But I will not!) I hope this brief glimpse of simplicity in method gives a good idea of a course of fire, designed for retention. At that possible close quarter defence of the Officers life.
In that twenty-five year span, no bystanders injured, one fatal shooting of an attacker, armed with a broken pint glass? One round straight through the heart, instant collapse, fired at 6ft.

The bullet was found on the stretcher, hardly deformed, it had gone straight through the body.