I use all sorts of targets. The rubber dummy is quite a good teaching model, as you see where an off centered head shot would really go.
Mental imagery is helpful plus it allows someone to assess the critical anatomy to hit.
Unfortunately, it also serves to subconsciously desensitize someone to shooting a human if the need ever arises.
A shot to the torso would get someone’s attention and make them think twice, assuming they’re not on drugs. A head shot has a small vital zone and is harder due to movement.
A more realistic assessment is to see how fast you draw from Concealment and hit the target accurately.
You bring up a number of points I dont think many even consider.
You are usually told to shoot COM, at a square on, nondescript/PC type target and all will be good. If youre going by and using the scoring rings on many silhouette targets, youre not even shooting where you really should be, even with a head-on shot.
What COM is, can vary greatly, depending on how the target is positioned in relation to you, in the moment.
You really need to have at least a basic understanding of anatomy, and where the real targets are in the body, and where you need to aim/shoot, to hit them. Dont just mindlessly shoot what you are told is COM. Same goes for head shots.
Not saying a head shot isnt a good thing, but like COM, there is a specific target youre trying to hit, and that changes your POA, again, depending on your position in relation to the target. You dont just want to shoot for what youre usually told/shown what the square on target is.
Even 2D targets offer good training, "if" you understand what and why youre trying to shoot, and where to aim to hit those targets. A 2d target may be flat, but depending on the positioning of the person in the picture, you still have to think and choose the proper aiming point for the "track of the bullet" to go to hit the right target.
Someone may look at the target after youre done, and try and tell you "you missed", when in fact, you actually shot in the right place, to make the proper shot.
The other advantage, although I'm sure some will balk and say its not proper, is that it does help you to get your head in the game, and teach/desensitize you to shooting "people". Lets face it, if youre carrying a gun, what are you practicing for, if not that?
The last part of all this is, putting all of the above together, and drawing and moving, moving and drawing and quickly shooting the target as you go, while youre moving and making good hits in the appropriate spots.