Last year I got a doe at 38 and a turkey at 51. Neither knew what was coming. If relaxed and the deer does not know I am there I would think about 50 but otherwise not more than 40 at deer. I also practice out to 70 but could go to 100 at our range. I just don't have any pins for that and have never tired beyond 80. My last pin is for 50 so even the 70 is pushing it. Just aim high and see where the arrows group. It really shows flaws in form better at longer ranges.
Way to go Dan on the 84 yard Elk. That is awesome. If you know you AND your equipment can make the shot I say go for it.