Kanban is a lean approach that enables people who are applying it to visualize their workflow and thus, be able to speed up their work and deliver valuable outcomes to clients. Kanban does not change scrum in any way and in fact, is another tool that makes the scrum team's work more efficient.
Since time to market matters to both the customer (since they desire new or upgraded products quickly) and the company (since they don't want to lose customers due to slow releases or lack of ability to innovate), Kanban helps companies achieve faster flow and better time to market.
The Kanban practice of representing the work on a Visual Chart/Board using rows, columns, and sticky notes helps the scrum team see their work more transparently. For example, as soon as the team builds their Kanban board and breaks down the work in the "Doing" column, they're able to see all the stages that the work passes through which gives them a realistic picture of the effort and challenges involved in getting items to a "done" state. When bottlenecks are visible, they can do something to remove or reduce them.
As another example, Limiting the Work in Progress (WIP) practice of Kanban helps the scrum team become more organized and focused while reducing low-quality work or team member burnout. Limiting the WIP involves placing limits on the amount of work undertaken in a certain column based on team member(s) capacity. This helps the team finish already started work first before starting new work. By doing this, the team ensures that the process or the person performing the process does not become overwhelmed with the sheer volume of work.
Lastly, "Manage Flow" is another practice where the Scrum Team inspects the work items flowing through different stages and focusing their efforts on increasing their flow. Usually, processes have scope to become more efficient and the final aim of this practice is to deliver process outcomes faster. Inspecting the Kanban board, identifying and removing impediments, or readjusting the workflow are some steps that can be taken to increase flow.
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