I believe Hornady is talking about 20 shot groups to determine your final zero NOT working up a load. A good zero that is centered inside the your rifles true probable group size in very important at long range. A 20 shot group will show you that. You could even dial the scope down 2 MOA while shooting the group so that you can easily shoot at a precise aim point on the target without blowing the center out of the group and loosing your precise aiming point.