Kanban is a true PULL system implementation in software engineering. It is a Visual Card. Pull System means there is a queue of work, which goes through a number of stages until it is done. When work is completed in a stage, it goes downstream to the next stage. When someone needs new work to do, they pull from upstream
Work In Progress (WIP) Limits
Limiting the amount of work in progress (WIP) helps Kanban teams keep a steady rhythm by making sure no one is ever overwhelmed. If you’re not limiting your WIP then there is no flow. Your Kanban Board is no more than a to-do list... If we don’t limit our work how can we see where the bottlenecks are? And if we don’t identify the bottlenecks in our process how can we fix them? Without WIP limits you will continue to pile up partially completed work in the pipe thereby creating the phantom traffic jam.
Adding to your WIP without completing anything just increases the duration of all tasks in the queue which in turn effects company’s profitability. Since software development is a creative process, there are times when you may need to put something aside when you are stuck and pick it up again later Or customers may not be available for testing when you are done. For that you need a buffer – but adding more tasks to your queue without completing existing ones is a recipe for disaster.