They do change when they get well seasoned,I try and be sure they are seasoned before I make arrows,and yes I also scrape and sand them in the mid section to reduce the spine some if they need it.
I also usually make them up when they are to the point where I am ready to make shooter's 1 at a time,adjusting length/spine and point weight so they all shoot the same,just easier that way for me and not so frustrating as when you make up several and some don't do right and then you have to go back and work with them. I do the same with shoot shafts.
I'm not the best shot in the world that's for sure but I know when it's me or the arrow that ant hitting where I look.
Got to love um when they fly good and hit what you are looking at.
Pappy