What's important is the reduction in functionality. I can't do nearly as much from my Watch as I can with my phone, and specifically I can't just browse through Reddit or Facebook. While I may interact with the same number of notifications, I interact with them for significantly less time (because there's not much to do with them from the Watch), and any such interaction is unlikely to cause me to browse my phone in a more general way.

So that's the key: the Watch frees me from the trap of "Well I'm already on my phone, so I may as well open up Instagram/Twitter and scroll through my feed again."

Don't you need your phone in your pocket to use it?

For non-LTE models, yes. But if you are notified via your wrist, you still have to go through the effort of retrieving your phone, unlocking it, and then tending to the notification before you get to the “time wasting” stage, and I think its that’s a barrier to entry that’s causing people to use their phone less.

Yes, I have a Series 2 so I need to have my phone nearby (or on the same WiFi) for the Watch to be useful.

The difference is that now I can dismiss notifications from my wrist and I am less tempted to actually unlock my phone directly, which is what was causing me to get distracted before.

I've noticed with watch notifications I'm far more likely to mentally dismiss them without losing my train of thought.

Phone notificaions, on the other hand, clog up the unlock screen, and seem to demand action when I pull down notification center and see old ones.

I still keep notifications low, mind you. Watch ones are still a distraction. But on balance I find it much less.