I find that once a thread goes beyond 5 pages (30 posts per page) it becomes hard for me to catch up and post because often by the time i've finished those pages another has already been added.

I think it is good to merge away with some of the "asked and answered" threads, but I also think sometimes it's best to start with a new thread if something major has changed.

Although only tangentially related I do like when a thread title is edited to confirm previous speculation like from "speculation: US to start charging for drinks" to "Confirmed: US to start charging for drinks" so I know the result of the speculation and can skip ahead a few pages to real discussion instead of just random speculation. Maybe at the point of confirmation we should just start a new thread, lock the speculation thread, and put the final post as a link to the new thread.

But random newbie "can I upgrade with my grandma's sister's brother's mile on my dirt cheap tour fare to Timbuktu?" should just get filed away since usually some sticky or master thread of FAQ already covers it.