I stumbled again over this just today, and I second @Ed_S’s impression that the line seems to move less than once per hour here on meta. I visited once and posted a reply to the Embedded replies topic, then came back to check again for new posts after 5-10 minutes - so minimum the line should sit at the 1h mark, but not at 3h/4h.
Edit:
Also, I visited a couple of times over the last 3 hours, but the line didn’t move.