There's a place for unilateral shrug training since compensation patterns typically come from one side being weaker than the other. If you know you have a weaker side, simply add a specific shrug variation to that side to fix the issue.
A standing one-arm shrug with a kettlebell is very effective. Hold onto a bench to stabilize the upper body, making sure to stand wide enough to create a stable base. Keep the back extended and pull the shoulder blade back and down. Use an incline or flat bench to target different areas and to learn stabilization of the scaps in different angles.
At first glance, it might seem that the title of this article is a double entendre (you know, like "Kid Rock Rules!"). I assure you, it's not. My linguistic reference of choice is not a music-challenged snowboarder but the Oxford English Dictionary, or for all you acronym lovers: OED.