Actually this is interesting , dowsing rods could be a way for your mind to express itself, kind of a translator, so logical (real world) clues about a possible treasure location could be expressed.
That would also explain why one needs practice, the more you dig empty holes the more you learn where to dig to avoid digging empty holes

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And also explain a more than average rate of success on real terrain, but zero on planted targets, where such clues donĀ“t exist.
Lets get back to real (electronic) detectors