The 3d shooting is the difficult part of this question.For hunting purposes in most instances with a flat shooting bow,one pin will be sufficient out to 30 yards.A less obstructed sight picture and one less thing to think about while dealing with the adrenaline.Two pins will do quite well out to 40 to 45 yards if you have practiced sufficiently,say one at 20 or 25 yards and the other at 35 or 40 yards.A 25 yard pin should be able to be held dead on at 30 yards with out to much concern.My preference is one pin set at 30 yards,I am very confidant to all ranges I am comfortable with with this.
On the 3d course if you want to shoot in a fixed pin class I would still want some decent gaps between pins so that I could see clearly.Ten yard increments such as 10,20,30,40,50.Or an adjustable sight with one pin.