I've heard of that idea before, which was part of the reason for my post. My pins are set at 10, 20, 30 & 40 but if a single pin can be good out to 30, then why have more than one or two pins?
When I shot a 3 pin sight, I had a slower bow. My pins were set at 20, 30, and 40 yards. With my new bow I could stretch my first pin to 30 yards with the others being at 40 and 50. I have a single pin type sight now that stays set at 30 yards for most situations. However, I still think I might prefer a 3 pin sight.