As far as I know, it has always been the case that one cannot start the same serial thread twice in a row. The poster of #1000 has 24 hours to make the new thread, followed by #999 and #998 24 and 48 hours later. After 72 hours, anyone else can make it. That will remain the same until the administrators rule otherwise.
That is news to me. I recall other back to back serial threads, and I also was under the impression that after 1000 the one with 1001 gets to start it.
Anyway, maybe lock this one and be done with it. CFC is serious business.