I think it’s good to go on adding to an old topic thread, if relevant, even months or years old. But unless you’re in Recent Discussions view, you’ll never see what someone’s just added, because in default General Discussion view an old thread stays lost, way down the pages - a professional forum/repository of wisdom shouldn’t be ephemeral like Twitter!
Writing this because I often find some vital discussion abandoned by main players, and I wonder if that’s just because the thread has dropped off their first page, so they stop seeing that people have answered.
Anyway, I only use this view to pick out the new threads. Dropping threads cannot be explained by this because as soon as you create one post, you get email notifications for new answers…
Neatly arranged in date/time order of most recent new comment in the whole forum regardless of topic - uncovers many unsuspected treasures incl stuff I wasn’t interested in at the time of previous appearance.
All other forums I value are organised in that format - only the over-clever Bentley forum went the way of making most recent new topic its default (like RC’s General Discussion default) in an effort to look more like social media.