Watch for cards that stay in Doing without moving

A card that hasn’t moved in several days is a signal about a real obstacle — examine it rather than adding more work.

Why it works

Stalled work cards are diagnostic data: they indicate a blocker (missing information, dependency, unclear next step, avoidance) that is invisible when work is managed mentally. The visual board makes stalls obvious without requiring active tracking. A well-functioning Kanban board has consistent left-to-right flow; a card that stops moving is a system signal that something needs to change — adding more cards to Doing in response is exactly the wrong reaction.

How to do it

1. Review the Doing column daily for cards that have not moved since yesterday.
2. For any stalled card, ask: what is the actual next action? Is there a dependency I’m waiting on? Am I avoiding something here?
3. Either identify a concrete next action and write it on the card, or move the card back to To Do and add a specific unblocking step to the queue.

Evidence

Bottleneck identification is foundational to the Theory of Constraints (Goldratt) and Kanban method: the system’s throughput is limited by its slowest constraint, and identifying the constraint is the first step to improving it. Application to personal work is a practitioner extrapolation. (mechanistic)

Theory of Constraints is well-supported in manufacturing; its application to individual knowledge work is conceptually coherent but the dynamics are different.

Sources

• Goldratt (1984), The Goal (Theory of Constraints — applied in manufacturing; principle adapted to knowledge work in Kanban)

Common mistake

Treating a stalled card as a planning failure and adding more tasks to feel productive — this is the classic bottleneck mistake: adding work upstream when the constraint is downstream.