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.
This six-week program breaks some of the currently accepted rules for workout volume and duration. That's why you'll do more than 20 sets per workout and you'll train for 60 to 75 minutes.
The purpose of this column is tri-fold. Purpose number one is as a "refresher course" for seasoned lifters. Sure, deep down, you may know this stuff, but it's been so long since you first read about it that you've forgotten the rationale behind the subject matter.