I've found that when people say that, most of the time they're talking about the meat, muscle, cartiledgeand junk surrounding the actual bone. Once in a while they hit the bone. In my opinion, people are quite liberal when they say it blew through the shoulder.
I tend to agree with David. It is more a figure of speech in many peoples' cases...unless we are talking about a rifle here. I was under the impression that a bow was not capable of generating enough KE to actually "Blow through" both shoulder blades. Maybe the edge of them but not right through. I am definitely out of date on my anatomy but isn't there different densities to a deer's shoulder area/blade?