For work I have incubated eggs for 2.5 days and took them out to slow their development for 16 hours before putting them back in. Most survived. However, add shipping and unknown weather, that would be tougher.
I would however believe in people incubating for 3 days to verifiy fertility, and sending fresh eggs. By 3 days of incubation, cracking open or candling and egg will show how many are fertile.
A hen can hatch all her chicks in a day simply because she does not start to set (incubate) them untill she has all she wants... for some silly hens, it is more than they can deal with and they end up with very few chicks because the pea brains try and set on more than they can cover.
Quote:
And that idea makes no sense at all. Once the embryo is at day 3, all the cells other than the gametes have become determined. In other words, they have a fate path to reach. There are already a few hundred if not a thousand cells in the blastocyst of a fertile egg (making that bulls eye), before the egg stops awaiting incubation.