What determines when my Apple Watch uses a haptic tap for a notification? Some notifications on my Apple Watch (e.g. Viber) use a haptic tap when they appear on my Apple Watch. Others (e.g. Facebook) do not. What determines whether a haptic tap is used or not? Is this something I can change?
From this Apple Discussion:

There are variations. The 3rd party app developers have some control over what you get, but they won't have been able to check it before launch - they'll have been using a simulator.

This can currently not be changed by the user.
To turn haptic feedback of:

Open the Settings app.

Scroll down and tap Sounds &amp; Haptics.

Turn Haptic Alerts on or off.