Stone walls passing over outcrops

Sometimes you wonder about why a stone wall does what it does when it passes over an outcrop. Sometimes the wall is interrupted by the outcrop, sometimes it seems to compulsively climb the outcrop and continue over and back down the side of it. And sometimes rather than wall there are a few isolated rock piles. I wonder if there might have been a law requiring a wall to be continuous in order to achieve proper status as a property boundary - so a compulsive climbing and crossing of the outcrop would re-enforce the legal status of the wall in its claiming of an enclosed piece of land. Sometimes the wall becomes a sequence of rock piles which, if not for the wall on either side of the outcrop, would seem to be a bit ceremonial.

For example (south side of Rocky Hill Rd) here are three such rock piles in a row:
In the fog, they have a 'feel' to them but maybe they are simply one form of compulsive outcrop crossing. That last one is a nice little pile, and certainly not built in the easiest way, if its only purpose was a legal requirement: