Yea I don't want my temps to go past 89 . But I I'm nervous if I drop to 88 that one of the tubs maybe at 86 and idk if that's gonna be to cold or not .
This type of variance is fine I have a 2 degrees variance from top to bottom (I have a big incubator and I have stop using a fan in it a few years back)
Eggs are a lot more resilient than what most people think.