In the ART Kanban some steps have work in process (WIP) limits.

 = WIP limits are necessary in the ART Kanban to ensure large queues are not forming, which would slow down the flow of value and increase the lead time. WIP limits are a way of applying the Lean principle of reducing waste and optimizing the system for the whole. By limiting the amount of work that can be in progress at any stage of the Kanban system, the ART can balance the demand and capacity, avoid overloading the system, and focus on completing the work rather than starting new work. WIP limits also help to expose bottlenecks, dependencies, and impediments that need to be resolved to improve the flow efficiency and quality of the work. References: = ART Flow - Scaled Agile Framework, ART and Solution Train Backlogs - Scaled Agile Framework, Kanban And The Importance Of Work In Progress (WIP) Limits