I try and do this now when I go out with the kids to the park so I'm not tempted to be buried in my phone.
If you really want a “smartwatch on your wrist”, because you’ve wired up all your home appliances into Apple’s ecosystem or some use case like that, then great. A smartphone’s battery life may be acceptable.
But if your use case includes, “track my heart rate 24 hours a day, my overnight sleeping patterns, and be an alarm clock and practical timepiece”, then paying hundreds of dollars for 18-36 hours of battery doesn’t really make a lot sense against the other options available now.
That's how I use my Apple Watch. But I don't leave it on for a week straight, I take it off and charge it when I hop in the shower. I haven't found a use case for the shower yet, but it could happen.
The one nice thing I've enjoyed on this version is I went with the one with cell service. I haven't used it a ton, but it -is- nice to be able to leave your phone at home. I wouldn't intentionally make or accept calls on it, but having kids you always want to be reachable so in the case of an emergency it works fantastic.