Poultry Talk Ontario (pto.ca)

Marking eggs with X and O, yes.
Do eggs have to get turned 180 degrees, or can they be turned 90 degrees each time. Each time meaning 3 times a day?
If not 90, then why?
I'm asking because I don't know how incubator turners work, and I don't think hens turn them 180 when they do.
Thanks.

Depends on the egg turners. The ones that fit into a little giant turn the eggs 180 each time. The turners in a incuview roll the eggs from side to side 6x a day. Hens are magic! I have used the x and o method and just turned them 180 each time and had successful hatches.

I'm sure others have a better answer than mine! At least more technical.

Degrees really doesn't matter. Mama hen doesn't measure degrees or count hours between turnings. 180 degrees more or less is easier than anything else for me personally, I pick eggs up, flip them (gently) ass over teakettle and set them back down. It's faster to just roll several at a time, but I always manage to crack some when I do it that way. It just matters that they're turned regularly, it doesn't matter how much.

Thanks!