4 pin sight for me. Almost every deer I have shot was under 20 yds but when so many other things can go wrong the less thought I have to put in it when the time comes the better. I recently changed from 20,30,40,50 yds to 20,40,50,60 yd pin. By placing the 20 yd pin at the top of a deer's back and the 40 at the bottom of the chest I am hitting dead center mass at 30 yds, and with having an illuminated sight the further the 2nd pin is from the top the less distracting and cluttered my 20 yd sight pin is.I clipped the lower 3 fibers from my pins because it looked like a traffic light in front of my face and I couldn't see the target behind the pins.
As far as one pin, I have only one pin on my son's bow because I do not want him attempting 40 and 50 yd shots until he becomes more proficient and stronger with the bow and then the 40 yd shots will be at the groundhogs in the food plot or a coyote passing by at further distances than what I want him shooting deer at.
By keeping his yardages shorter at 25 yds or less with one pin he is forced to learn patience and build more appreciation for archery hunting and the skill it takes to get that animal so close for a shot.
When I was younger I shot instinctive, I wish I would have continued that but I went with a sight when I was 16 and now I'd miss horribly if I were to try shooting by guessing.