Sorry guys I meant to say using the sight window as a distance reference. I found some stuff online actually. On a 20 yard shot you would sight your bow about 1 1/2 above the strike plate and aim closer to the strike plate for shots further away. You can make marks on your sight window for yardage reference. I think its all about tilting the bow.
The Olympic archers use sights, same idea/concept only I'm talking about just making marks on the bow for reference. It takes some practice but I think once you have it nailed the grouping should improve.