We have always been amazed that our backyard EE line lays x-large eggs and all all year around without light. I had an inbred rooster (2 generations) and bred it back to it's mother and a Production Red. The Production Red was a very good layer about 5 large eggs per week. The mother EE laid 6-7 days a week for almost 2 years all large eggs . She is 7 years old now.
The Production Red's baby lays 4 times per week all x-large. The very inbred EE from the mother EE lays 6 days a week but eggs are small by USDA standard. So I weighed 6 small vs 4 x-large. The six small weighed 11 ounces. The 4 x-large weighed 9 ounces.
So after all of this rambling, I found that having a small Excellent 6 per week layer is just as good as having a Very Good 4 x-large per week layer. The only difference in the eggs was the amount of white. The yolks are the same size.
The inbred EE is a very beautiful bird with muffs and beards, a pea comb, and blue eggs.