I've also had positive results with a staggered hatch. Set 10 Feb 11,12 and 1 on Feb 19 and two on Feb 20. 10/13 hatched and are all doing great. Growing like little weeds. This was my first go at hatching. I have a Little Giant still air and turned by hand. I kept the second group separated from the first hatch with a plastic fruit container with lid cut off turned upside down. I could still reach in turn eggs add water ect and the first babies did not trample the still incubating eggs. The fluctuactions in temp and humidity that were unavoidable during turning and hatching did not seem to adversely affect hatch rate. The second group of eggs were also refrigerated prior to going into the bator and 2/3 of these hatched!!!! I did have some sleepless nights watching hatch TV and moving chicks to the brooder as soon as they were dry to prevent disturbance of the other eggs. Have fun its great to see them hatch 21 days seems so long!!