You should see what range will allow you to consistently place all of your arrows in the kill zone. Practice out to that range and beyond. HOWEVER, when you are hunting, many other factors can come into play (nerves, moving deer, concern that you'll be discovered by the deer to name a few) and you should consider your maximum kill range to be significantly <u>less</u> than your practice limits.

Your concern for accuracy is commendable. I hope others strive for the same goals.