I understand now.
"Immediate" results in a notification for every post in a thread, live. The result is redundant notifications. If a single thread gets six new posts before I check it, I have six notifications. This is how Facebook used to work, a year ago, before they updated to their new...
When are "daily" notifications determined and sent? That's my default. But while "immediate" caused a stream of duplicate notifications, "daily" results in almost none.
All threads are reset with the transition, I've found. You'll have to click the last page link to get to the latest pst, and have the forum learn that you're caught up on every thread.
Adam, thanks. This is helpful. But I'm still confused, as I don't get update notifications for all items I follow in the menu bar item. I think I've got all the options turned on. The system is ... daunting, with many user settings and viewing perspectives :)