The Intention of Iterations, Time-Boxing, and Flow with Cadence

This article describes the intention behind cadence and time-boxing in Scrum and Kanban.

Cadence

Cadence means to have a regular beat. In Scrum, sprints provide the regular beat. The start and end of a sprint provides timing for the following.

  • Ensuring the product backlog is ready for the sprint
  • When to do planning for the sprint
  • When to see what has been completed
  • When to demo the work of the sprint
  • When to do a retrospection

Time-Box

It also provides a time-box within which to fit work. This “time-box” is from the time after planning to the time we set for the end of work. The sprint probably has another day for the demo and retrospection. Scrum’s time-boxing has some interesting side effects which are quite useful such as the following.

  • Stories must be small enough to fit into the time-box. Rather, they should be small enough to take no longer than a third to half of the time-box. We prefer even shorter.
  • A set time to see what’s been done and stop working whether done or not.
  • A reality check on if stories have been completed or just coded.
  • A deadline that keeps things a little bit urgent but not too urgent.

Scrum suggests teams plan these time-boxes. Without such a plan, you would essentially just have cadence. Scrum’s structure provides a great degree of discipline for the teams. This is one reason Scrum is a good starting point for many teams wanting to become Agile.

Kanban’s flow model does not require a time-box. However, a cadence to do the above collaborations is useful. In either case the cadence provides for different teams to have a set time for collaboration.

Summary

In summary, sprints provide the following.

  • Cadence for:
    • Input
    • Output
    • Demonstration
    • Retrospection
  • Discipline
  • Small batches
  • Visibility of work pulled by the team
  • Visibility of work having been completed by the team
  • A method for planning
  • Focus on the work to be done during the next sprint

Time-boxes require the cadence of the events to happen at about the same time (beginning and ending of the sprint). With a flow model, you can decouple when these different events (e.g., input and retrospection) occur. However, without time-boxes, teams must be more disciplined on their own. Nothing stops a team from working on overly large stories.

Lean-flow models suggest having more visibility than just what is being pulled, what is in process, and what has been done. Scrum has been slowing suggesting more visibility as it evolves but Kanban requires it. Of course, there is no reason Scrum teams can’t use the policy of having explicit workflow reflected on their board.

Note that with time-boxing or cadence teams can measure their velocity. With cadence, you just measure the amount of work that was completed between the cadence points.