Dogs can surely mess up a hunt, anytime from opening day through sundown on the closer. They have tremendous value in putting birds in the bag. If you're hunting without dogs, you're shooting more birds than a limit, if you're filling your bag.
I think fences are a bigger risk than broken glass, no one litters much around here, mostly because there aren't many of us to do it.
I guess here's something for you to consider: If you think the birds are concentrated in fence lines, canal banks (whatever those are) and roadside cover, you might want to see what they're concentrated like in stock dams, sloughs and weed patches out in the middle of private ground.
I am not sure I agree that when I am dogless (as I am right now) that I am shooting more birds than a limit (and yes, I often do fill my limit). I have lost cripples no doubt, but I have lost them with dogs too. There's very little doubt a good dog increases chances of finding a cripple but that doesn't mean I always loose one before limiting out. Far from it. That just makes me want to hunt the fence lines and field edges even more as if they hit the ground in a spot I can see and if they are crippled, I can often swat them if need be, though that is a fairly rare need.
Canal banks is an Idaho and Montana thing. There's usually some cover left along the canals that flow water to the fields.
I love hunting the thick cattail soughs, and do quite often when birds are in thick cover. I don't mind getting in the middle of them and pushing through, especially if they're not too tall. I rarely hunt private ground but have on occasion. I'd like to more as the birds for sure seem much less pressured.
