As a couple of folks have said this is a topic that has been beaten to death.Having said that I would never discourage someone from asking a question.There will never be consensus on this issue.
My personal belief is that there are to many variables involved to shoot at a whitetail deer at 60 yards.Shooting at a stationary target on flat ground at a known distance is a world of difference than shooting at a non stationary animal,while perched 20 feet in the air when your shivering from the cold and your heart rate is twice what it would normally be.I routinely practice at 50 and 60 yards and am very competent at those distances but I would never shoot at a whitetail deer at that distance.Shooting proficiency is something we should all work hard at,and we should work hardat putting ourselves in position to make the shortest shots we can.