Yes, good point. It does seem that it all comes down to three things- luck, Human presence, and monitoring with luck probably being the leading factor. An too, I've recently been wondering if road closings also allow monitoring stations to be set up without being observed along with the other more obvious reasons of course. I mean in this day and age monitoring makes good sense as it saves man hours in the field and that translates into the money on a limited budget to be better used elsewhere.