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Work In Progress Limits
Definition: A Work in Progress (WIP) Limit is an explicit rule that restricts the maximum number of work items that can be in a specific stage of a workflow at any given time. It is a core practice of Kanban and Lean methodologies, designed to prevent overloading teams and to improve the flow of work.
Core Principles
Stop Starting, Start Finishing This is the fundamental mantra behind WIP limits. By limiting the amount of work started, teams are forced to collaborate and complete existing tasks before pulling new ones.
Key Insight: This simple rule shifts the team's focus from individual busyness to collective throughput and value delivery.
Expose Bottlenecks When a WIP limit is in place, a bottleneck downstream will quickly become obvious. Work will pile up at the stage just before the bottleneck, and the team will be unable to pull new work until the bottleneck is resolved.
Example: If the "Code Review" column has a WIP limit of 3 and it's full, developers finish their coding but cannot move their tasks forward. This forces the team to address the code review bottleneck immediately.
Reduce Context Switching When developers juggle too many tasks at once, they lose significant time to context switching. WIP limits reduce this by encouraging focus on a small number of tasks until they are completed.
Improve Flow and Predictability By preventing overload and smoothing out the workflow, WIP limits lead to a more consistent and predictable
Cycle Time. This makes forecasting and planning far more reliable.
Relevance in Engineering
Without WIP limits, it's common for teams to have many tasks started but few completed, leading to long Cycle Times and a feeling of being constantly busy but not productive. Implementing WIP limits is one of the most powerful changes a team can make to improve its development process. It creates a pull-based system where work is only started when there is capacity, leading to faster delivery, higher quality (due to increased focus), and a more sustainable, less chaotic work environment.