There is absolutley no standard for this........really
Total agreement , wind being a serious factor . 30 is around the longest I like to shoot , but I had a doe come in and stand perfectly still at 35 and I was on the ground , had ranged the distance , and it was my longest shot , cant see those circumstances happening very often . I killed my best buck ever last year , at 10 yards , and have passed at 20 before , on what I felt was an iffy shot .