I will say that Mr. O'Connor would probably have had to walk a fraction of those distances if he'd had good dogs with boots. The dogs can handle the terrain, but you have to watch them for overheating if it's still warm out.
One place I will not hunt my dogs on Gambels is in the Eastern Mojave in a particular area covered in Cholla (pn "Choy' ya) Cactus. The 2" tines will penetrate the sides of most good hunting boots for hunters and they are brutal on dogs. The small clusters of tines on the ground cripple dogs thru their boots.
"Almost all of my Gambel's quail hunting was done without a dog, as FEW DOGS can stand the thorns and the thirst of typical Gambel's quail country."......Jack O'Conner
Chuck-
After 55 years plus hunting in the desert, I agree with Mr. O'Conner.......We almost always limit out on birds, understand their habits, how to hunt them...enjoy the walking, enjoy the desert,
enjoy the other wildlife that dogs run off etc.......so find no need for our canine friends........
The area's we hunt traditionally are covered up with Cholla-a.k.a. Mexican Jumping Cactus, Mesquite, Barrel, Prickley Pear and many other cacti species......

Best,