Can't help you with Phoenix or Tucson, but here is my layer stats...
I live in Yuma and I have 9 chickens that "should" lay eggs.
4 PBR 3@ 11 months, 1 @ +2 years unk- Average 21 eggs/ week
1 RIR @11 months average- 5-6 eggs /week
1 Leghorn X @ 2years- average 6eggs/ week
1 White Rock @ 8 Months- avg 2 eggs/week
1 Black Australorp @ about 7 months- Not laying
1 Delaware @ Unk- avg 2+ eggs/week
This is conservative as I generally give away 2 dozen eggs per week.
They get no extra light and thier cages are well covered by citrus trees. My neighbors never knew I had chickens even though they are in the front yard!
Three of the PBR and the RIR were raised from feedstore chicks. They had the proper nutrition at the proper stages. The LeghornX was purchased from a knowledgeable poultry raiser so it was in good condition when I got it and layed after a week of settling in.
One of the barred rocks is finally completeing a molt. I bought the black australorp, Delaware, and White rock from someone else and they had poor nutirition as the grew up. Plus, I am unsure of their age. I suspect that they will produce more eggs as their nutrition increases. I gave them Calf Manna on a suggestion and it seemed to work, but they still are not up to par with the other chickens.
I feed them primarily layer pellets I get at the feed store and occasionaly layer mash I buy at
Walmart. I like the pellets because there isn't any "powder" left over that isn't eaten, and that ends up being about 10lbs per bag of waste in my eyes!
I add some scratch which I throw on the ground to keep them busy and every now and then a handfull of cracked corn. They get table scraps. I also have a tractor that Is 9X9X3 that I put in the yard and they scratch and eat grass.