Every state has non-productive areas. I'm basing my opinion of coyote population on what I have been told by callers that live elsewhere and have called in AZ. They report how easy it is to call coyotes down there vs. most other places they've called.
Personally, I think the main advantage is the large amount of public land like you said and a larger coyote population and prey base in some areas. I don't think the coyotes are any dumber or smarter. Probably just more of them competing for food.
Heck, if you based coyote population on what was taken during a contest, people would think there are no coyotes in the NW. Every time we have a calling get together here, very few coyotes are taken. I think someone spikes the food with coyote repellent or something.
I'm going to change my response to this thread to "just call when you can and do your best".
Good luck
