Would Grooving the shaft help keep them straighter?
Not necessarily a Lightning Bolt Pattern.
More like Fullers, three of them spaced evenly around the shaft.
This method is used to strengthen and lend rigidity to other materials... Why not arrow shafts?
Similar to corrugated street metal roofing tin.
Perhaps pressed or hammered into the shaft instead of cut in.
Just thinking out loud...
-gus