I have taken a few neck shots ; they were all with in 20 yards.there I know I can hit a quater,so I will take that one. over 50 yards "NEVER"
if you go high,they fall but will get up.low they will go down and get up and may not find them,(they will die later).
it all depends on the person and there ability to hit the spot.
get a chart of deer vitals and look at the neck bone.it is not where most people think,it is low at the back and higher at the headalmost in the middle.
http://home.mn.rr.com/deerfever/Anatomy.html