I'm inclined to agree with Victor on this. If the time between posts is significant, then the thread has gone cold. If the same person posts with new info at that point, no one will ever have a reason to revisit the thread. The obvious alternative is to start a new thread with the same subject matter but i don't think anyone wants that. Those would be very specific circumstances though, a dormant thread updated with new information by the same person who was last to post before it went cold. Very easy to identify.