Old watch - yes, this is true.I've compared my watch's readings when the nurses at the Dr office took SpO2 readings and they all have been with 1%, I think that's quite accurate. And in fairness, when you get your SpO2 measured at the doctors, they typically do blood pressure as well and you are sitting still for a minute or tow or more, you should use the same behavior when taking measurements with the AW.
For me personally, nighttime measurements are more meaningful than during the day and I check my vitals on the phone every morning for that
Watch 10 - it's WAY off. 85%, 92%, 94%, 95% when doctor machine 97% today.