RE: 20 yard mental barrier
Actually accurate shots can be made even with very poorly tuned arrows. When I shot the Howard Hill in 2006, I'd only had my selfbow for a short time, and hadn't had a chance to make any arrows for it. I shot my longbow arrows, just for the heck of it. If I did everything just right, they flew ok--but most of the time they were putting on moves that would make a Russian gymnast jealous. I won with those arrows......
The arrows I shot are 75-80# spine. My selfbow "likes" 45-50# spine.
Not to say that better tuned arrows aren't easier to shoot--just that poorly tuned arrows won't always cause poor shooting. Poor form and poor focus pretty much guarantees it most of the time.
I like Art's advice.
Chad