Overall I get about 3 to 4 notifications from Facebook per day, so the quantity isn't too high. It also helps me avoid the habit of frequently loading Facebook to check for new notifications when there usually aren't any.
I have a few users on https://movinggauteng.co.za using web notifications for transit updates. I'm intentionally not sending many for now, because I'm still working on a way for commuters to choose when to get updates.
