We always do staggered hatches with great success. W also do dry incubation. But then we live in Florida and have lots of natural humidity. We generally will fill half of the incubator on one day and then candle on day ten. The bad eggs get replaced by new ones and also fill the other half of the incubator. When the first set of eggs are on day 19 we put them in our homemade hatcher/brooder. We then candle the second set of eggs, bad ones are replaced and the empty half is refilled. This goes on for 9 months without stopping. We end up with 90 - 95% hatch rates.
I have two bators one I use mostly to incubate and one that I use for day 18 and beyond and that seem to work for me? Look under the incubating threads there is prob some one who really knows what there are doing I am a newbe still good luck
My understanding in order to do a staggard hatch you have to have two incubators, one for day 18 and beyond, but you still can't add eggs to it until the ones in lock down are done. and an incubator for days 1-18. As it says in the other post if you turn up the humidity on eggs that aren't ready for lock down they will likely drown because it will decrease the air pocket.