Column WIP limits…
… promote excessive trial and error. Practitioners are recommended to “play with the column WIP limits” to find out what works. Rather than measuring the effects in terms of throughput of the whole system and deciding accordingly, this approach proceeds without guidance and without a specific goal in mind. It is basically seeing what “sticks to the wall” and what “feels comfortable” for any given column owner(s).
Do not hurt yourself!
Quoted from: Tame the Flow.