As a positive note, now that I understand it a bit better (I hope!) I think the Unread > All Unread at the moment has the most useful functionality for how I want to use the forums.
(Screenshot from "Unread > All Unread" link on the Lived Experience side)

++++(Big Pro) I can see all the new posts that I haven’t read yet (grouped by the thread if the "Discussion" tab is selected by default, excellent). I'm not limited to a list of ~5 threads or posts, so I don’t have to open up each subforum and look at them individually to get a proper amount. Win.
Question for curiosity's sake - When we say "all", how far back does "all" go? Is there a set 'beginning of time' for this function or is it literally all since the forum was created?
-(Minor Con) I can't see any new ones that I just read. But I see there’s a way to fix that under the Options if I want to mark them all as unread again.
-(Con) I can't see who made the latest post. Only who made the thread.
-(Con) I can’t see when (date/time) the latest post was made.
-(Con) I also can’t tell if they’re in reverse chronological order (newest to oldest by latest post timestamp, as would make sense but I can’t be sure because there’s no timestamps.)
-(Con) I can’t see when the thread was created.
-(Minor Con) I can’t see a preview of the text of the new post. The preview is for the original post of the thread. I can understand the logic of this. Just goes against my personal preference but I understand why people may like this.