I bought a small farm in the area known as the Big Country of Texas, which is traditional native quail habitat. Like they say, a bad year on quail hunting here is still better than what other states have to offer. Everything I listed above. There you have it. One area that I would like to point out that doesn't get mentioned often, and that is ranch management.
Ranch management plays a HUGE role in quail numbers.
But what the rancher does with his resource is critical. This year I hunted over 20,000 acres of ranch land and saw the whole gamut . I also saw some good pastures with moderate amounts of grass and vegetation necessary to sustain large coveys. Yes we found quail on the overgrazed pastures but that's not the point. Some of the pastures were plum scalded.