Shooting in the shoulder tends to anchor critters better than shooting behind. I generally want to be 2/3 of the way up or so. If you shoot low, the meat is thicker on the shoulder so you lose more meat and it doesn't anchor as well. On smaller parcels of land, it is handy to anchor quickly, as it can be a pain in the ass to locate the adjacent landowner to get permission to retrieve your animal. In rugged country, especially on bigger animals like elk, it is handy to anchor the animal when said animal has the ability to make its retrieve much more difficult by running down a mountain with no road access to the valley, into blowdowns, etc. What many people would considered a shoulder ruined in its entirety can be salvaged mostly by separating the muscle groups and scraping the clotted blood off the outside.
