i would say it depends if your using the chronograph or not , omega states 50 hours power reserve . maybe they stated a lower number so it wont fall short even if you are using the chrono for a bit . idk
I think Omega is guaranteeing that the watch will run within METAS specs during the first 50 hours but not for the extra remaining 10 or so afterwards.
50 hours I guess with the chrono activation
without ~66 hours
Neither of mine last anything even close to 50 hours. My new white one is off at omega because it only lasted 8 hours. The new black one is I bought to wear while it’s gone lasted 15 hours today. None of my automatic omegas last anywhere near the stated reserve either. I’m getting disappointed with the brand at this point. No they were not mistreated or overwound, I literally got the black one yesterday.