A deeper view of how Kanban works in practice — the six core practices, flow math, and cadences. Complements kanban.md (the reference card covering board, WIP limits, key metrics, and Kanban-vs-Scrum).
The Big Picture
Kanban (Japanese for "signboard" / "visual card") came out of Toyota's lean manufacturing in the 1940s and was adapted for knowledge work by David J. Anderson around 2007. The core idea:
Visualize your work, limit how much you do at once, and optimize the flow of work through the system.
Unlike Scrum, Kanban is not a framework with prescribed roles and events — it's a method you layer on top of your existing process. You don't reorganize the team or rename anyone's job. You start with what you do now and improve incrementally. (See the four principles in kanban.md.)
The Six Core Practices
Where Anderson's four principles are the philosophy, the six practices are the actual mechanics:
| Practice | What it means |
|---|---|
| 1. Visualize the workflow | Put every work item on a board with columns for each stage. |
| 2. Limit WIP | Cap how many items can be in each stage at once. The heart of Kanban. |
| 3. Manage flow | Watch how work moves; smooth out bottlenecks and stalls. |
| 4. Make policies explicit | Write down the rules — e.g. column entry/exit criteria, definition of done per stage. |
| 5. Implement feedback loops | Run regular cadences to inspect and adapt (see below). |
| 6. Improve collaboratively | Use models and data to evolve the process — Kaizen (continuous improvement). |
Board Detail
A more featureful board than the basic backlog → done flow:
┌──────────┬──────────────┬───────────────┬──────────┬──────────┐
│ Backlog │ To Do (3) │ In Prog (2) │ Review(2)│ Done │
├──────────┼──────────────┼───────────────┼──────────┼──────────┤
│ ▢ ▢ ▢ │ ▢ ▢ │ ▢ ▢ │ ▢ │ ▢ ▢ ▢ ▢ │
│ ▢ ▢ │ │ │ │ │
└──────────┴──────────────┴───────────────┴──────────┴──────────┘
↑ WIP limit ↑ WIP limit ↑ WIP limit
Add structure as needed:
- Sub-columns — split "In Progress" into "Doing / Done-but-waiting" to make handoffs visible.
- Swimlanes — horizontal rows for separate work types (features vs bugs) or priorities. An "expedite" lane lets urgent items bypass WIP limits with explicit policy.
- Class of Service — different SLAs per card type (standard, expedite, fixed-date, intangible).
Work is pulled, not pushed: someone finishing an item pulls the next one only when they have capacity. Work is never assigned or dumped onto a busy person.
WIP Limits — Why They Work
A WIP limit feels restrictive — that's the point. When "In Progress" is capped at 2 and both slots are full, nobody can start new work until something moves out.
Why limit WIP?
- Surfaces bottlenecks instantly — if items pile up before a column, that stage is the constraint.
- Reduces context-switching — fewer items in flight means more focus and faster completion.
- Improves flow — doing less at once gets things done faster overall (Little's Law, below).
- "Stop starting, start finishing" — the team's mantra.
Rough starting point: 1–2 items per person per stage. Then tune based on what the data shows.
Flow Math: Little's Law
The metrics in kanban.md are tied together by a single formula:
Average Cycle Time = Average WIP ÷ Average Throughput
Plain version: the more you have in progress, the longer each item takes to finish. Cut WIP → cut cycle time. This is math, not a tactic — it holds whether you like it or not.
Visualizations
- Cumulative Flow Diagram (CFD) — stacked area chart of items in each stage over time. Widening bands reveal bottlenecks; a flat region means a stage is stalled.
- Cycle Time Scatterplot — one dot per completed item plotted by completion date and cycle time. Reveals predictability (tight cluster) vs outliers (long tail). Useful for setting realistic SLAs.
Cadences (Feedback Loops)
Kanban doesn't mandate meetings, but mature teams run regular cadences. Unlike Scrum's coupled ceremonies, these run on independent rhythms — replenishment and delivery happen on demand, not on a sprint boundary.
| Cadence | Purpose |
|---|---|
| Daily standup | Quick sync. Walk the board right-to-left ("what's closest to done, and what's blocking it?"). |
| Replenishment meeting | Refill the "To Do" column from the backlog. Replaces Sprint Planning. |
| Delivery / release | Ship whenever work is ready. Continuous delivery is common. |
| Service Delivery Review | Inspect flow metrics, SLAs, and customer outcomes. |
| Operations / Risk Review | Bigger-picture process improvement and risk management. |
The critical difference from Scrum: planning and delivery are decoupled from any fixed iteration.
Choosing Between Scrum and Kanban
Covered in scrum-vs-kanban.md — includes the Scrumban hybrid and a decision guide.
Quick Cheat Sheet
KANBAN IN ONE BREATH
Visualize work on a board
└─ Limit WIP per column ← the core mechanic
└─ Pull (don't push) work as capacity frees up
└─ Measure flow (cycle time, throughput)
└─ Improve continuously (Kaizen)
NO sprints · NO mandated roles · NO fixed iterations
CHANGE anytime · SHIP anytime · START where you are
Glossary
- Kanban — "Signboard"; both the method and the card on the board.
- WIP limit — Max items allowed in a stage at once.
- Pull system — Work is pulled by available capacity, not pushed by assignment.
- Lead time — Request → delivery (customer's clock).
- Cycle time — Work started → done (team's clock).
- Throughput — Items completed per time period.
- Little's Law — Cycle Time = WIP ÷ Throughput.
- CFD — Cumulative Flow Diagram; visualizes flow and bottlenecks.
- Kaizen — Japanese for continuous, incremental improvement.
- Swimlane — Horizontal board row separating work types or priorities.
- Class of Service — Card type with its own SLA and policy (standard, expedite, fixed-date, intangible).
- Scrumban — Hybrid of Scrum structure + Kanban flow.
The mental shift from Scrum to Kanban: stop asking "what can we commit to this Sprint?" and start asking "how do we keep work flowing smoothly and finish what we start before grabbing more?"