They need different price points. Not everyone will spend the money for a .001 arrow. The .006 shaft and the .001 shafts are made the same way, same materials, machines etc. They sort them based on their finished tolerances and then label them as a Pro, XT, Hunter etc. I cut at least one inch off the back of my arrows no matter their listed tolerance. Then cut the remainder off the front. Been doing it this way for years. Always use an arrow square before installing inserts and nock adapters or nocks as well. Weigh your shafts and all components before installation to get all the finished weights the same. I never buy .001 arrows anymore. Almost always the .003. I have shot many 300 5 spot rounds with .006 shafts built in this way. I didn't watch the posted video, but you really can make an excellent arrow out of budget minded tolerance arrows without much trouble at all.
Yes, that is 7.9 grains per inch of arrow, not per pound of draw weight. A 28 inch arrow that weights 7.9 grains per inch (plus components, nock, vanes, insert, 100 grain point) will weigh about 385ish grains. At 70 pounds draw weight that is 5.5 grains per pound.
roger that. I probably missed it, but didn't see where he mentioned his draw weight. that left the only thing to compare to was the grains per inch of his current arrow.