Not all threats will be face on, and static.
Many trainers and instructors also use three dimensional targets , and moving targers such as NTI, and Awerbuck is known for his "unique" targets.
Hence the reason I was raised to shoot moving and three dimensional target presentations, beginning at a very very early age.
-VCAs do use cover, whether intentional or not- the reality is, one may not have full view of face, neck, or head.
Intent is expressed by verbal, and non verbal language, and one might have to stop a threat that is "obscured" , by cover, and have to shoot the best target presentation.
i.e. BG is shooting at you from out and around behind your fridge. Your best shot might be VCA knee, or foot, that is exposed. If the threat continues, and VCA steps out, and at angle - still moving- one shoots to stop threat, and this might now mean a bullet has to get past arm, to enter thorax from a an angle.
Same thing if VCA is using the breakfast bar, that is part of kitchen cabinet and decor, if they are shooting at you from down, around and from the side of that breakfast bar.
[I prefer slugs for shotguns, so with a slug, I could punch through that bar, through pots, pans and whatever else is kept in that cabinet area, and get to VCA.
FMJ 45ACP, or 9mm, even standard pressure 158 gr, .38spl LSWC will to , based on my actually having done so.]
VCA using the shrub near a carport for concealment and you arrive home ( bringing in groceries for instance), and now the shrub becomes cover against you,
Bullets deflect, they all do.
Rifle bullets deflect hitting twigs and deer are missed.
Awerbuck has shared 12 ga slugs being deflected off the brim of a ball cap, worn by a VCA target.
IME, solids deflect less when shooting glass.
I have tested this, over and over again, with various media, including glass.
Threat might be on the other side of glass Eterge', or glass "knick-knack" display you have in the home, or business.
It might be the decorative glass door in the home, which leads into main dining room, etc.
True.
One of the Set Ups (ya'll call these stages) I did ~ 30 years ago, was based on a real event.
Nineteen year old female, stepped onto a icy porch to get the paper and in breaking her fall, broke her strong side arm ,and hurt her wrist. In getting up, she went down again, and her knee required surgery.
There she was in a recliner of the day, after getting home from the hospital, and in a bad way.
Well, we had elderly folks, with arthritis and some had it so bad, they were under NO RECOIL orders. Osteo so bad, they could no longer drive, even being a passenger was a "concern".
IF they shut the car door too hard, or the trunk, they could break a back.
So getting into a minor fender bender, was a concern for their health as a passenger.
My aunt had Osteo so bad, she stepped out of bed one morning , and broke her foot.
This nineteen year old, fell asleep in the recliner, and did not know her dad had come in early from work and was putting a knick-knack in the display mom had.
It scared the nineteen year old.
Other elderly folks had expressed the same concerns - "risk for falls".
Risk for falls is not an age thing.
One couple had known me forever and about ten years ago-
One of my elderly couples had a serious situation. Husband was brought home after out patient knee surgery. She got him home, he got into his recliner.
His wife left to get his meds, and some food from a a mom-n-pop grocery store that did prepared foods. They wanted her to come get some food, already cooked, so she would not have to cook for a couple of days. Just how mom-n-pop stores are with customers they have known forever.
She was attacked in her carport, as she arrived home. She was targeted at the drug store, and tailed, and then followed home. She unlocked the door off carport, and brought in one box, went back out and BGs were using her car for cover, and attacked her.
Knocked her down...she did not break anything, just some bruises and small cuts...
Husband is just home from surgery and still a bit under the anesthesia, and he cannot get up , and if he could what could he do? Thank goodness the bad guys just stole her car, her purse, the meds, and food and took off, without coming inside to where he was.
(He normally pocket carried a J frame, just he thought he would be best not too, just coming back from being under anesthesia...and ....)
So going back since I was wittle, mentors did set ups, so it was only natural for me to do one based off that Nineteen year old and her situation.
Only natural I would do a carport attack one...
So the set up I did some 30 years ago due to the 19 year old female incident, and concerns of elderly-
Set Up.
-Strong hand and arm are disabled. We used a temp cast, and mitt.
-Recliner, kicked back.
-.22 cal handguns, due to NO RECOIL orders such as a Doctor and Physical Therapist do impose.
Handguns were snub nose revolvers, in because these are small, easy to conceal, and therefore one can have on person, even in the home.
VCA was a moving, target filled with dirt. A scarecrow, if you will, behind glass "knick-knack" display cabinet, (eterge') with plastic toys to replicate knick knacks, on glass shelves. This thing was between five and six feet tall and about 18 inches square.
NO start buzzer. We rarely did start buzzers, instead we used starts such as gunshots, screams, doors being busted into, glass breaking, and the like.
Reality, as there are no start buzzers in real life.
I prefer standard pressure, 40 gr, lead round nose.
If I cannot have that, then a 40 gr high velocity.
Now a variety of loads of the day were used...
Since that time I have replicated this same set up, for assisting folks with more modern loadings.
I vary it a bit...
Some loads are designed to "scatter on impact" , and they "scoot" out of a bore really darn fast, even faster than hi-velocity ( hyper velocity).
Investigate & Verify.
I have, lots of times over the decades, and it might surprise folks of some of the results.
Get a piece of the most simple, plain vanilla glass, like from a window pane.
An old window with panes are best, instead of loose panes.
Now shoot a target from 7 yards.
Repeat with this glass anywhere from 12 inches, to further away from that target ( glass closer to you).
Repeat at longer distances, if you have a glass interior door in the home, replicate the setting, such as where you would shooting from, and where threats would be.
I got one for you.
No secret , I am not a fan of low recoil buckshot loads for shotguns, especially one brand.
a. That load deflected something awful shooting through a interior glass door.
b. That "rubber ball" in that loading will come back at you, and hurt you.
The ball hit one of the cross sections were glass panes are held in, and bounced back with authority.
A standard pressure, 40 gr lead round nose, fired from a Beretta Bobcat, grouped right nice, through that door.
[easy door we made , to replace glass easy and fast, for this teaching and assisting tool for new shooters and CCW folks.]
Investigate & Verify.
However, it would be most likely that I could see the badguy's face/neck/head in the typical home defense scenario. 
