for questions related to "work in-progress" (WIP) limits
See "Limit WIP" in the core practices section of Wikipedia's Kanban development page, which says:
Limiting work-in-process implies that a pull system is implemented on parts or all of the workflow. The pull system will act as one of the main stimuli for continuous, incremental and evolutionary changes to your system.
The pull system can be implemented as a kanban system, a CONWIP system, a DBR system, or some other variant. The critical elements are that work-in-process at each state in the workflow is limited and that new work is “pulled” into the new information discovery activity when there is available capacity within the local WIP limit.