From a clubmaking/fitting perspective you hit on the correct heft match for you specifically with the playing length/lie, shaft weight and other fitting factors yadda yadda. Everyone has a target number that they hit well. Found by impact testing (below). This is how you truly custom fit a golfer. When you find a fitter that does impact testing you have found a true custom fitter/builder. You can self fit and this would be the start of finding the correct fitting factors. BTW this does not mean that at shorter playing lengths with the same lighter graphite shaft will produce the same impact.
You'll find that many golfers will post a specific club (poon club) that they always hit well many will say a 7i. This is also why swing weight matched clubs are not the end all to be all as the letter/number will not match impact as you go thru a set. Swing weight as an industry standard and is done as it's the easiest way to build a 7g interval 1/2" playing length set. But that does not mean the same letter/number say D-0 at 5i 38" shafted will have the same impact as the same shaft 9i at 36" D-0 or insert any letter/number.
