I use three.
Top pin for shooting almost straight down.
KP...that seems odd, to me. I have practiced the straight down shot.....and I use my 50 yd pin to hit my mark. Same thing on a 3D target we had set up in a tournament one time at 2 yds.
Interesting.
I have 4 pins on my sight....and I wish it had 5. I like to PRACTICE at the longer distances a lot. I will shoot 80% of my shots at home from 40yds and beyond. I usually start at 40......shoot a few at 50......and then shoot my last few arrows at the shorter distances.