I don't mind having multiple/recurring threads on some topics. They serve different purposes: my main goal was to raise awareness on an event that seemed neglected by my country's newspapers. Then, if people catch up on the issue, it will be easier to engage in follow-up discussions when we get more data. I also enjoy to read the speculations and flow of thoughts of posters from different backgrounds.

It's not specific to HN. And I guess a regular agenda might do. I'd guess that's how journalists make sure to follow up with things in the "this day 3 years ago x happened" articles?

But I agree I'd like a dedicated place for such reminders.