colobohl

That may be true for you and your setup but all carbons are different and the spine will change with each setup and arrow type.You can cheat a stiff arrow and put a heavy point and get the spine right for groups.Penetration may suffer as a result.You can also do the opposite,use a lighter spine arrow with a light point and it would do great indoor.The problem would also be penetration and it would hate wind.

My point is that some carbons need 9% for one person while needing to be 13% for someone else.Penetration is best in the 10%-12% range(IMO)as long as this will allow proper spine.

If some do as you state,12%-18% foc it may make the arrow to week in spine to shoot accurately out of their bow.I do like 12% for a carbon provided the spine will allow it.