There was a discussion on a previous group about the eggs that are hatched in higher temps, they say Roosters hatch from the higher temps, that the eggs that contain pullets don't survive the higher temps but that the Roosters do, I got told to stay at 99 as close as possible, I do hatch cockrels and I also hatch pullets at that temp. Percentage wise on the Bantam Marans chicks and Araucana chicks I've hatched I had more pullets than cockrels from the hatches. Almost 3 pullets to every cockrel that I hatched, at one point I could have put Quads together.
I purchased an Old GQF Cabinet Incubator and the Old Man that sold it to me said not to touch any of the temperature adjustments, they were set exactly as they needed to be and he said he always got good hatches, he told me he'd hatch 2 to 300 chicks at a time, so I left everything just like he told me. It runs at 99.5 or pretty close to that.
Victoria