I look at where I hunt and say to myself.. what is going to be the average shots and probably the furthest shot I might have to make. I then sight in so that at the average distance and furthest away, I do not have to make a scope/sight adjustment. For instance, where I hunt 35 yards is more then average and 50 is just an insane long distance. So I sight in at 35 yards, knowing that at 50 yards, if I HAD to take a shot, I can aim dead on.
On my field rifle, my long shot is 100 yards, my average is a little over 50 yards. So I sight those rifles in at 70 yards and then I do not have to make any adjustment.