Not for sure about the crop impaction part at all but I think I remember reading about how yogurt is good in small doses but to much can cause watery stools. Also when my chickens got stressed from a near stray dog invasion they all had the nasty watery runny poops. Sorry it not more info but...
We do left to right and I sell eggs as well. I have 8 birds.
I keep a 1/2 carton for my odd eggs (ones that don't fit carton well because of shape or size) I pencil date on those. Our family eats those first. Sometimes it stays full and sometimes its empty. If empty then we go the full carton...