Well, I guess it would be OK for one topic to be assigned to multiple sections.
I don't think there would be a need for anyone to review every thread. My guess is most of the threads won't be assigned to any virtual section.
It's not a cataloging system. So there is no need to every single thread to be assigned. More like a way to tie multiple threads into a single logical collection.
I'm not sure how it will work out. That's the reason I started this discussion.
I have some ideas about how it should work. But that doesn't mean that users will actually use it the way it's intended.
It might work even for "temporary" or time-sensitive topics. Let's say there is some event that generates a lot of interest among users.
Maybe some super-giant quilt-related trade show.
Lots of people would make new threads about it. Questions before it begins, pictures after it ends, and some other stuff in between.
Grouping all those threads into one virtual section dedicated to that even would be a good way to preserve it and let anyone interested in that even quickly find all threads about it.
All those threads would still be accessible from the "real" sections such as Main and Pictures.
There would simply be another way to find them.
I don't think search would work as well for that purpose.
As I said, that's just one example I can think of on top of what I already described. Who knows how this system will be used.