I have a buddy with a pressure gauge on his arbor press. Just out of interest, I seated a 4x fired Dasher which had not been annealed and a new hydroformed case, right along side an annealed hydroformed case, and an annealed 4x case. Definitively, the seating pressures were NOT the same for the old vs. new non-annealed. The pressures for the annealed cases were. Same load in each case, the ES’s and SD’s weren’t terribly different for each set, but if I lumped my new brass and old brass together, my velocities, ES’s, and SD’s stayed the same. For the mixed non-annealed brass, the ES and SD of the new & old mixed lot was greater than either new or old. Simple so see, if a person knows how to look.
I’ve known a lot of guys who have never annealed and swear they could not benefit from doing so. Usually these are guys who never end up mixing new and old lots of brass, which helps them stay consistent. I had a guy try to convince me chasing a low ES was a waste of time because he had 1/4” groups at 100yrds with an SD of 40... I took him to my 600yrd range (not fair to take him to 1,000)... guess what happened? Lots of guys will also say their accuracy can not be improved by neck turning. I’ve met lots of guys who swear by full length barrel bedding, others who swear by “pressure pads”...
I anneal on any precision loaded cartridges. Don’t care two shakes if someone else doesn’t.