I went to Pelz school years ago and they used this formula. Every chip should be hit so that it lands three feet onto the green and then rolls to the hole. You determine the club to hit by subtracting the roll/carry ratio from 12. If you need it to roll 5 times as far as it flies, then 12-5=7 -- use a seven iron. Consider your pitching wedge to be a 10 iron. So if you need to carry it 10 feet and roll it another 20, use the PW.