Other variations on the thought: What if the limit was only on the number of unsolved threads? What if it was an absolute limit per adventure?
I've started a thread (ha ha?) at https://plus.google.com/108395059461267285712/posts/Fdp29mGgQJs
Not sure if it'll spark discussion, but the thought made me wonder. I've yet to try it, but I suppose a side effect could be a more focused adventure, given the number of slots was small enough...maybe.