The only time it would be accessed is when the user goes to the "Favorite Thread" page that lists their threads. It would grab all their thread ids from the favorite table then look up the thread title in the thread table, a simple join could be used to accomplish this. It then shows the threads to the user.

But the whole email notification system needs to be reworked so that Favorite Threads are the threads that get email notification. Just like Fusetalk does it. So replying to a thread isn't needed to put it under Email Notification. I talk about it all the time so I should get to it an write it. I haven't donme it because it would require some major hacking to database to accomplish it.