That's a real sense of responsibility that you did not miss to merit a post even when you are out of merits. Keeping track of all those good posts is a work itself.
Not really, I only tend to look at that list when I'm piling up with merits, and my new source allocation is coming up. Although, most threads that are in that list, are actively discussed since they're usually good quality discussions, and therefore I just happen upon them again.
The list isn't also regularly maintained, and for the above reason a lot of the posts I've happened upon again with regular browsing, and likely merited it already. So, the list rarely gets used, especially since recently I've been making a conscious effort to exhaust my merit allocation every month.