we are doing staggered hatches.
for the 3-4 days we turn the humidity up, we have found it doesn't really affect the other incubating eggs.
we have a redwood cabinet incubator, so what we do may not work for other styles. we do still pop it open once, about midpoint, during "lockdown" to quickly turn the eggs that aren't ready. as soon as the last chick has hatched, we drop the humidity back down. i've watched air cell progression and the 3 days has not affected it. the air cell is created by moisture moving from a 100% humid environment (inside the egg) to a less moisture-saturated zone (outside the egg). 3 days of humidity being 20% higher outside is not going to affect moisture moving out of the egg that adversely. it is still going to exit the egg. the moisture would still leave the egg if the outside humidity was 99%, as there is always a struggle for equilibrium.
out of the viable eggs during the last 3 hatches, we have had hatch rates of 85% (one died trying to get out, the other died a couple days before hatching; this was the first hatch, not really a staggered), 100% and 100%. incubating and hatching in the same unit, just placing trays that would hatch first under those that would hatch later. our 4th hatch is this weekend (we've done turkeys and chickens).
i know this will incite some people, but i don't accept "no you can't because this is what i have been told"
to be totally safe, though, i think you would do well to purchase the 2nd incubator (saw it in your sig)
