Anecdotal: In more than 35 years of loading, shooting, collecting, etc., and having owned hundreds of rifles, I have had (and still do) one single rifle that will make one ragged hole only a little larger than the diameter of the bullet at 100, yards from sand bags on a bench with no coffee that day. One.
I don't have any that good, but I hope to encounter one one day!
What I can't figure out is why people don't demand proof. You're charging big bucks for some supposedly accurate rifle? Meet me at Gunsite Hills, show me, and I'll pay you and for the range time. Otherwise, it's your treat.