My $0.02:
New watches should perform within 1-3 seconds a day, vintage ones (30-60 years old) should perform within 10-20 seconds a day. Older watches (pre-fifties), well, that is a different story.
This is reasonable I think, and especially for properly regulated Omega 500 movements. Even inferior movements can show such performances. My AS1701 in my Glycine perform within 10-20 seconds a day. My H-694A within 10-15 seconds a day. I have other examples as well with Valjoux and Venus movements.
Of course a movement could be worn or damaged in such a way that expected performance could exceed the 10-20 second range. In most cases, I don't believe that is the case. With proper service and exchange of parts, you still should expect a performance within 10-20 seconds.
It all boils down to costs, the way I see it. Who pays to get the watch properly regulated?
COSC apart, for me 30 seconds are in the higher echelons of what I personally find acceptable. But then again the double of that (a minute) should not be acceptable for a vintage watch from the fifties or the sixties. We are talking about the golden age of mechanical watches here.
Ah. You expats. Just love to poke fun at Norwegian peculiarities...
Joke aside, we don't wear mechanical watches for accuracy. Plenty of digital watches take care of that. Bottom line though; a minute is too much.
Later, Jim.