This is why I came up with the idea of the chart and feel the need for my own spine tester. I'm just getting start in Traditional Archery, so if I'm wrong in my thinking please correct me!!!
The thing with arrow spine, is there is not really a standard set. What I mean by that is if you order arrows from several different places that are spined at 45#, and you tested them they would more than likely be different.
If you look at the spine charts from different vendors they all very from one another.
So to have your own spine tester and finding the deflection/spine your bow likes would help in making and possibliy buying arrows. Where instead of ordering a spine weight you could maybe, see how they measure their spine weight and then ask for a certain deflection, for example .423.