The rules need revising, but thank you for being amongst the few who went to the trouble of reading them. I actually rewrote them a year or two back to be much less... essay-like in length, but it seems that the old, cumbersome list has somehow resurrected itself. Hmm...
Anywho, just use common sense when approaching a typical thread with a view to continuing the discussion. If you want to be certain that the topic is still alive and well and being added to, then use the "Recent Posts" or "Unread Posts" links in the secondary navigation bar to bring up a list. Regardless - don't worry about it. If a topic hasn't seen any active for a few days but I feel there's still life left in it, I'll still post in it, and you shouldn't feel put-off, either.
Welcome to the community, by the way.