I had a duck sitting on eggs and hatched six of them when she got off the nest. There were still around 20 eggs in the nest. I took those eggs and put them in the incubator. Doing the math, if the six hatched at 28 days and the understanding duck eggs hatch between 28-35 days, I was on day 42 and three more hatched but the membranes were dry and had to have assistance hatching. Luckily they all survived and are healthy. Has anyone experienced this before? Are really late hatchers normal?