Sometimes this happens if you allow your Apple Watch to update over cellular connection as long your iPhone is in your possession, and the Apple Watch is at least 50% charged. My S1 did that a few times back in the day where it would update while I ran errands 😂Not sure if this is new or was introduced a while back, but I updated to the beta released yesterday on my Ultra with it still on my wrist. There was a time when it would only update if it was on the charger no matter what the battery life was. I took my watch off the charger at 3AM yesterday and updated it at 3PM, so there had to be a some drain. I was surprised to see "Update Complete" while sitting in the dentist chair.
These things are based on the users choice as well. I recently traveled so my sleep stages kind of got wonky with so many awakes as the air conditioning in the hotel rooms were so loud that it would wake me up. But in Vitals app it did not change the duration as much. But as Peaks also measures your sleep quality in order to determine your energy levels it went down only a few percentages.Yeah, I guess if you need to or want to track all that stuff it is important to some. None of the vitals or metrics you mentioned mean a lot to me, but I get it. I am in pretty good health. I do track all of my workouts daily which is pretty much Peloton and Weight Training. My resting heart rate is 59. I check it at work every now and then. Blood oxygen too. I just don't need to know what it is when I am sleeping.
The workouts I do are mostly Fitness+ workouts in my home gym, which are Pilates with Marimba, Dance, Anja’s Rowing, Yoga with Jessica/Jonelle/Dice, Core and Strength. I also take a walk outside when it is not so hot.