One pin is all anyone needs as long as he or she knows exactly where the shaft hits on the POA at distances greater or less than the sighting-in yardage. I was using one pin on recurves in the 60's and on my compounds in the early 70's.

However, regardless that today's compound bows, even some recurves, are capable of greater energy, there is no such animal as a "flat trajectory" with an arrow off any bow. Additionally, the degree of drop is highly individual to the person, to the bow, to the arrow setup, and with height and angle, etc.

Although your bow might be considered a high-energy bow (fast), when you sight in at 20 to 25 yards, other factors might be putting that arrow on the mark at its peak of trajectory. Therefore, the arrow might drop very quickly past the distance of sighting in. Correspondingly, if the arrow is peaking its trajectory at 20 or 25 yards, a 10 to 15 yard shot off the pin-setting might send the arrow very low below the zone.

Set the pin at a fixed yardage, but know positively where the arrow hits at less or greater yardage the sighting-in distance, and from the heights and angles you will be shooting from and at when in actual hunting conditions.

What works for one, seldom works for all.