If you keep humidity and temps even, opening the bator isn't a thing. I KNOW lots of people scream it to the rafters, but I just don't have a problem with it. Now it's probably my bator - it's not foam, and my being used to making adjustments but I stagger hatch in a small homemade bator. While one group is hatching I have eggs to turn.
My temps stay in the 99-100 range and my humidity 50-60 % and voila, hatch and turning same time. If I have to I mist if it drops below 40% briefly it doesn't do any harm. I dry hatch so I'm not trying to keep the really high % some folks are trying to keep.
I have to PAY attention but it's not all that hard to balance out. I did everything the way I was supposed to with the old foam bator and had poorer luck.
I turn three or four times a day whichever I remember to do. But I just do it and compensate.
While keeping to rules is useful ... they're not molded in steel. And getting a feel for the bator you have and what you can do and compensate for has it's uses.
Use your nogin, read your thermometer, know what your hygrometer is off by - yes most are off by some.
And keep your wits. The world will not come to an end if you have to open that bator.
I have yet to meet three chickens that do it the same way either.
