I'm no expert, but I've been gardening here in St. George UT (basically northern AZ also) and I don't think it's possible to over water (within reason).
I've made 10" deep raised beds with homemade compost over the existing clay and they've worked okay.
I've made a couple of sunken beds about `10" deep in the clay, and back filled with compost, and they've worked okay. Very poor drainage with the clay, and I still can't seem to water as much as they'd like.
I recently made 3' tall raised beds back filled with
wood chips to about 2', and then the top 10" or so is homemade compost. The beds are on solid
concrete with no earth contact. They've performed the best for me, but they take even more water.
Everything I have is on 2gph drip emitters. I also occasionally (maybe once or twice a week if that) soak them by hand with a garden hose.
I run the zones in the in ground sunken and raised beds six times a day for five minutes each watering cycle. (35 minutes a day!)
I run the tall raised beds six times a day for seven minutes each cycle. (42 minutes a day!)
The soil is bone dry to my middle knuckle in all the beds before the start of each watering cycle. I'd water twice as much if I could.
Last month I used 15,000 gallons of water including water usage for the house. In January I use about 3,000 gallons of water (obviously nothing is being watered in the garden at that time, so I'm using 12,000 gallons of water basically for the garden!!!)
I know, it's not going to make some people happy to read that, but those are my real world results.
There is no sand or perlite, or any type of drainage material in my compost. It holds water fairly well in my opinion.
105f average temperature here the last two months. No rainfall whatsoever for the last four months. Humidity in the teens or lower most days. 3,000' elevation. Also very windy.
I'm a bit ashamed to admit all that, but it is what it is.
Good luck!