I don't know if ducks would be the same as chickens, but, I'm sure pretty darn close when it comes to coming out of an egg.
I had to do a save this July with some chicken eggs the day of hatching, as mama hen went psycho on me. I had no incubator,just a heat lamp. I got a couple of eggs started, as I didn't want them to suffocate on a drying membrane from improper humidity.
Of the 3 that I helped to start by breaking a small hole for them, 2 survived and are now 13 weeks old and very healthy.
I had held the eggs to my ear, could hear them inside, I lost many from not helping, just eventually died, so I felt I had nothing to lose really.
the hen was on 15 eggs, 3 were bantam x eggs. I got 7 viable babies with just a heat lamp, and my lap and my daughters lap.