Noticed this on a recent flight, and got me thinking.

How often are flight attendants still walking around and preparing the cabin for landing when the plane actually touches down? On a recent flight, the cabin crew were still securing items in the galley when the plane touched down. They thought they were higher than they were, so they weren't seated and strapped in. Does this happen often? I thought the pilots would signal the crew some how (like how they signal they're passing 10,000ft) before touching down so the crew would have time to strap themselves in.