Ducklings can take a couple days to fully hatch from the time they pip. I let my broodies handle it. If they leave eggs, then I’ll check them and incubate then if still viable, but the broody should be able to handle the hatching. She will also keep them plenty warm, even in very cold conditions. I observe for ones that may get away from her and not find their way back, but usually they stay right close to her.