I understand that you recommend the 9,7 and 5 iron for chipping. But why not also use 8 and 6 for the distances inbetween?
If you use the 5,7,9 iron chipping combination you will begin to see a huge improvement in your scoring around the greens. If you want to fill in with a 4,6, or 8 iron, give it a try. However, make sure you become masterful with the 5,7,9 first.