The last three deer I shot I aimed for different spots on the shoulder area but I will try to explain as I answer you questions as best I can with a keyboard.
1. Most importantly, can someone post up an image with a dot showing exactly where you aim for the shoulder shot, please?
With the provided link to the pictures, using the first one with the red dot, The difference was my deer was standing slightly more towards me, and I aimed to the area where the base of the neck junctions the shoulder blade. At the shot the deer simply crumpled. In looking at the diagram above you can see that my shot passed just under the intersection of the spinal junction of the neck and back bone as well as took out the opposite side lung and most of the heart. This particular area is very vulnerable to the hydrostatic shock from a bullet moving through it. With all of the nerves it quickly incapacitates the game and they hit the ground.
2. Do you ALWAYS, SOMETIMES, or NEVER also hit a lung with this shot? Ever hit two, or just one, or neither?
Sometimes yes sometimes no, it depends on the actual angle of the game. With a little more towards a quartering shot the chances of hitting both lungs go down verses more of a broadside shot.
3. (related to #2) Does this shot ALWAYS, SOMETIMES, or ALMOST NEVER require a quick coup de grace follow up shot?
I have never had to make a second shot on deer or hogs using this shot placement.
4. Does this shot always require a full broadside, or can you get away with a quartering toward or away? If so, how much on quartering away, and how much on quartering toward - 15 degrees, 30 deg, 45 deg, 60 deg, what, on each? And still have it be an effective shot? Requires a smaller angle of quartering toward or away than a heart/lung shot, before feeling confident to take it, or about the same?
My basic reason to take such a shot is to put the animal down on the spot, meat is not an issue at this point in time. I generally use or try to use this particular area in very dense forest, or when conditions do not favor following up on something that has run. I have no issues with the angle if I can put it through the base of the neck or junction of the neck/spine, and still get through to a lung or heart. Quartering towards or away, the angles might change but the intent is still the same, to put the game on it's nose right where it stands.
5. (related to #4) Do you always hit both shoulder blades, or just one, or what?
Sometimes I do not hit either, as mentioned it depends on the actual position and movements of the game.
6. How far do they run, on average, with this shot? If it depends, then what does it depend on?
If they do run, which some try but do not succeed, it is only a few yards at most.
7. Would you ever take this shot with a bow, with say, Muzzys, or gun only?
I would not attempt this type shot with a bow simply due to the ability of the arrow to skim under the hide over the top of the shoulder blade instead of actually penetrating through it. Also there is, as has been mentioned, a LOT of heavier bone in this area which will also hamper penetration.
This said, I aimed for a spot similar to the first one with the red dot on it, for my first archery buck. Difference being his onside leg was in front instead of back like the one pictured. At the shot he ducked, and the arrow hit him squarely between the shoulder blades and through his spine. He did rock three feet or so sideways, but recovered and headed off in high gear, not going around the small trees and bushes but through them. I knew it was a good hit due to the way he was running, but we found no blood what so ever. The buck made it close to 80 yards and piled up in some 6' tall grass on a pipeline. We tracked him as best we could and still couldn't find him. That evening the buzzards had found him when my friend returned, and I finally got to him about 10:30 that evening. Needless to say he wasn't good after laying there in 80+ weather. However the shot destroyed a couple of vertebra, and exited just in front of his offside ham, leaving gut to plug the hole. The shot was at 22 yards and penetrated through almost 3' of deer and still exited. I did not open him up to look, but based upon the initial hit and the direction of travel, I hit the backside of the offside lung as well as the liver on the way through.
8. Do you have an opinion as to whether, *generally speaking*, it is more desirable or less desirable than a neck shot, when given a choice?
I try to use this type shoulder shot only for a true trophy deer, other than that I would just as soon let them walk on by, or hit them between the ribs. I have taken many shots to the neck, only due to knowing the anatomy very well. I knew exactly where I was shooting and what the result would be. Most of my shots to the neck are withing the white circle under the chin, with them standing looking straight at me. this is not a recommended shot for newer hunters, or folks who haven't boned out their own deer taking note of how things are located. For seasoned hunters however it is a viable option which generally does them in on the spot. I have shot deer in the spot marked in the second picture from the link and had mixed results. When they are looking straight at you it's hard to tell if there is a little bit of uphill or downhill angle to the body. If the rear is lower, there is a good chance you might shoot right through the deer and not hit anything vital at all. Been there done that saved by a quick follow up. With the rear end higher, there is a chance your going to make one hell of a mess and still have to track your deer.
These might or might not be answers your looking for but they are from my field experiences through the years. I have take many deer and hogs from many different angles, and I always try to learn something from them all. I do inspect the damage inflicted and analyze the shot after getting the hide off and having them dressed out. It helps not only from my hunting knowledge but also in developing the loads I use, or the arrows, broadheads, and bow I shoot.
