Two years ago, I published this article about trying to find a healthy balance with Apple Watch notifications.
Some are useful because they reach you when your iPhone isn’t around. Others let you decide you can respond to something later without getting distracted with your phone. Most have no benefit and risk making you more distracted by your watch or numb to notifications altogether. Apple Watch alerts from iPhone are all on by default currently. You can turn them off app-by-app, but you’ll need to repeat this for every new app download.
I think notifications on Apple Watch should be off by default even if they’re on for the iPhone app. With the current default, Apple should at least include a toggle to disable watch notifications and turn them back on individually. A new system could be much more sophisticated, allowing watch alerts for certain contacts and specific type of alerts from apps. In the meantime, reversing the current behavior or adding an off toggle for all apps would help.