Hi Bart, i agree with what you say in almost every respect as all this case prep plays only a small part to accuracy in the reloading process... though for some people(like me) they're obsessed with getting the absolute best out of their ammo
In regards to case neck turning i was under the impression that by turning the high spots off the case necks it helps to align the projectile true with the bore, even though yes it will be a very very miniscule amount.
Happy shootin!