I was wondering about COSC specs, how it's the movement that is tested, and also about how autos behave when worn for only a day, etc. Etc etc. All getting murky and muddled in my head.

Let us say I bought a watch with COSC certified movement.

Each week I would put it on on Monday morning and wear it all day everyday until Friday evening.

Where would be the threshold of inaccuracy where I could say to the manufacturer, "excuse me, but...."?

I know that some people get lucky, and find that over the week the watch gains just 10 seconds or something. I'm wondering how unlucky you have to be before you get to ask for the dice to be rerolled.

I imagine answers will want to make reference to specific manufacturers