I'd shoot at least 60 in the perfect conditions....light clothing, light wind, deer feeding, broadside, not alarmed, known yardage, etc. Never had the opportunity yet.
In the worst of conditions...fairly windy, heavy clothing, still not alarmed though, I'd lower that to 30-35 yards.
Personally, I've found that deer are much, much less likely to react to the shot over 30-35 yards, and if they do....well, the deer isn't even there by the time the arrow gets there.
30 yards is the average distance I like to set my stands for, which is an all around average shot for me and very easy to make....but to each his own, everyone has their own abilities and they definately need to stick within them.