Our first setting hen was technically "due" today. I hauled her off her nest (squawk!) to check for any progress. She was down to two eggs and neither is showing any signs of hatching. We'll give her until Sunday to see if anything happens.
If these eggs turn out to be duds, we may test the hen's tolerance for another three weeks of sitting in one spot by slipping another six or eight eggs underneath her and seeing what happens.
All that hard work, wasted!