A setup like the one shown in the image attached, when the observer detects an update, will cause the piston to activate repeatedly, however the redstone never lights up. If a piston or sticky piston is placed adjacent to the raised block with redstone on that is facing south and the piston pushing the observer is facing north or east, the piston will not activate, If a piston facing east is placed adjacent to that block and the piston pushing the observer is facing north, the piston will not activate. If the piston pushing the observer is facing north or east, pistons facing downwards adjacent to the raised block will not activate. If the piston is facing south, a piston on the west side of the raised block will not activate but a piston on the north side will activate. In many other cases pistons adjacent to the raised block will activate and redstone components other than pistons seem to always activate.