Whether you coat the board edges or not depends on the results of your reliability testing, and your use environment, or what your end user specifies. In many cases board edges are not coated.

However I know of several manufacturers of free standing air-conditioning units, the sort you see everywhere in Asia, that use our equipment to coat the edges of their PCB control boards in these units.

This is not the easiest surface to coat on a board, and prior to them purchasing Asymtek equipment they were doing this by hand, with a brush.