Column WIP limits…
… will teach the team about swarming, and developing productive ways to communicate and interact when solving problems together.
Just thinking and taking decisions about problems together is usually a great improvement over other approaches; but the true benefit comes when the team actually acts together to resolve problems.
A positive swarming behavior develops naturally when reacting to column WIP limit breakages. This is unlike other approaches where swarming is dictated (often with the excuse of being lean and caring about one-piece-flow).
Swarming that develops naturally is way more effective and efficient than any imposed behaviour. The benefit is not so much in the swarming behavior as such; but in its natural, organic development made possible by the frequent, recurring breakage of column WIP limits.
Read more in: Tame the Flow.