On shipped eggs from the same breeder shipped exactly the same to the same receiver, I also agree with Stony, but cannot pretend to be nerdy smart, I'm more like the enabler brother, who I will always think of as Joel.
I think despite our best efforts, sometimes we only think we are incubating and hatching the same way every time, mainly because we believe our instruments used to monitor temp and humidity and they can be erroneous. I can add water to the incubator and have humidity register exactly the same as if I just set at least 20 eggs - so I stopped adding water. That may be due in part to the very low ambient humidity here, although I would think the opposite would be true. The last two hatches I did the exact same thing with the eggs, and the ones that came from nearest me were a complete failure. The only difference was I put them in the 1588 with the turner made for it, and put the others in the Farm Innovator 4200 with its own turner. The 1588's turner made creaking noises a few times, it is brand new, and I suspect it does not work as smoothly as the other. Maybe just enough to disrupt the hatch? Around day 11 or 12 I saw movement in only one egg, and even that one was no longer moving on day 18. I don't remove the eggs from the turner to candle because I don't want to jostle them too much or risk dropping them (I am somewhat less than graceful) and I would rather err on the side of caution. I keep the lid off only a minute, touch the candler to the end of each egg, I will go back and look again if I am unsure but I get it done quickly and get the lid back on. I've taken to only candling somewhere between day 10 and 12, then again when I go to hatching mode. I still don't have a great hatching rate on shipped eggs, but better than before. I am just now incubating my first eggs laid here at home, and should know in a week how well they fare in comparison.
The second incubator contained Fogle RIR eggs and some Black Silkie eggs, all shipped, and so far I have 4 RIR and 2 Silkies hatched, today is day 21. Another RIR is pipped and I am hopeful for a few more in the next day or so, but very happy to see those lovely chicks out and healthy.
Best news of the day, for me anyway - I am ridiculously happy to report my broody has hatched at least one egg, looks like one of the two Fogle RIR eggs I gave her, the other is a Black Silkie egg. She is a first timer, hatchery Blue Cochin, and I am very proud of her. I had to stop myself from giggling with glee when I spotted the shell and heard the little peeps coming from beneath her.