What's the (aimed) lifetime of a discussion on Tildes?

It's somewhat of an unspoken rule on Reddit that replying to a comment that's more than a day old is a faux pas. The conversation naturally settles within that period – or, less often, within two days. After that, the only appropriate thing is to either reference the conversation, or quote parts of the comments in relation to a similar issue in another post.

On Hubski, conversations could go on for days. It's explicitly stated in the guidelines that it's completely okay to reply to a comment of any age. I've never seen a year-old "revival" do any good, but the fact that it isn't prohibited or frowned upon adds no burden to the user.

How does Tildes handle this? Is there an unwritten rule already? Should there be a written one? What would be the factors?

Today's Feb 13. I've found a post from Feb 2 that was on a subject of interest of mine, where comments were insightful, but I feel like not all questions that need to be asked have been. Surely I won't go about creating another topic just to revive the conversation against only my own commentary to show for it.

There's also the matter of important, (semi)official topics on Tildes. Suppose a new issue arises that concerns an earlier public discussion held, say, half a year ago. It's a minor issue, but one that requires a discussion to settle. Does one comment on the old official topic, or does one create a new topic for this purpose?