Hey there les-jcbs, I answered there. But here it is, cut-&-pasted :
I would say that: "terrain clues" start for any person, even when out-of-visual line-of-sight. For example, you start walking a certain direction, on a hunch. Then as you get closer to whatever set of trees, a prominent rock outcropping, a cellar hole foundation, etc... That THEN you are in line-of-sight, for the "subtle terrain clues".
Thus: The terrain clues eventually present themselves for WHATEVER direction your hunches tells you to start walking to. And it wasn't the rod that gave you the "hunch". Or the eventual "terrain clue". It was all in your brain and mind. Just as it is for any skilled md'r who wonders: "Where's the best place to start?"
But, let's just assume for the moment that this explanation is not adequate to explain how someone could have a "hunch" for something that is outside their visual range. Ok ? Let's just assume that ... therefore ... the rods *must be doing something* that "hunches" and "terrain clues" did NOT tell the operator about. Ok. Then all I can say is: This would be all-the-more-reason to let it be subjected to tests. If you're saying it's beyond random chances, subtle terrain clues, eventual odds, and so-forth, I'd say : Fine: Then with that level of confidence, then it would seem like all-the-more-reason to gladly let it be tested @ DBT.