Amy, I am one of "those people"! In my cabinet, I thought if so many people recommend 70%+, let me try it. So I bumped mine to 70% last night on first pip. This morning I had one chick hatch who broke his yolk and still has a clotty vein attached. Second chick hatched in physically good condition, but after hours passed they were still wet and sticky, and both were lethargic. So I dropped the humidity to where I had it last time, 60-65%, and they are drying and fluffing. I am using 3 hygrometers, 2 of them calibrated and the third calibrated to the other two, and they agree!
Plus my pippers started zipping within minutes.