I agree with crooket.
I believe footings were inplimented to fix broken arrows to begin with. Today they are used for decoration , repairing arrows and adding werght forward.
I've only had one arrow loose spine and that was a sourwood shoot arrow that hit a hard object head on. The arrow didn't break but it would not fly well no matter what. It looked like a windmill going down range. I refletched it, changed the cock feather orentation and anything I could think of but it never flew well again. That loss of spine was from one trama and not over time.
With arrows as with bows there is a difference between dry wood(or cane) and seasoned wood with the latter being preferable.