Borrowed Time: Kanban Flow Debt
Excessive debt slows progress and can become a huge burden. However, debt is not always bad and can be necessary to meet project goals. Nevertheless, debt must eventually be repaid.
Flow debt in Kanban project management works according to the same principle. In this article, you will learn how Kanban flow debt is defined, how to measure it and how to prevent your flow debt levels from increasing in an uncontrollable manner.
What is flow debt?
Flow debt is when the cycle time of a task in progress is reduced by borrowing cycle time from other tasks in progress. Team members preferentially work on this task at the expense of others in the process. Any shift in priorities, deviation in the management focus or other interruption in the middle of the process can generate flow debt.
As with financial debt, the short-term benefits of accumulating flow debt can be worth the long-term costs associated with it. Focusing all team efforts on resolving an emergency may be the best course of action. In these cases, it is essential to understand how build ups of flow debt affect your whole process.
The delay of other work items is the less costly effect of the flow debt. What is more crucial is that the flow debt has negative impact over the predictability of your whole Kanban workflow and makes your estimates less accurate.
Measuring flow debt: Approximate Average Cycle Time
The cumulative flow diagram is an extremely powerful tool to analyse the efficiency of your flow over time. The horizontal distance between any two lines on the CFD represents the approximate average cycle time for the chosen workflow stages.
The CFD can only show us an approximate average cycle time because there is no way to verify if the tasks that are entering the process are the same as the ones that are leaving. The CFD does not tell us how much time any task has spent in the process.
The process data used to generate a cycle time scatterplot gives the exact average cycle time for a chosen time period, calculated from the cycle time of each delivered task. The difference between the approximate average cycle time and the exact average cycle time represents the Kanban flow debt.
When the approximate average cycle time is close to the exact average cycle time value, all tasks are moving through the process at around the same rate. No tasks are being completed much faster or slower than this average. When the approximate average cycle time is greater than the exact average cycle time, work items are getting stuck in your process. You are accumulating flow debt – the greater the difference, the greater the debt.
WE UNCOVER THE EFFICIENCY OF YOUR WORKFLOW
Optimise your performance with Kanban analyticsExplore Your Data Now
Little’s Law Assumptions
Complying with the Little’s Law assumptions increases the predictability of your Kanban process. The fourth assumption is:
“The WIP average age should remain the same, neither increasing nor decreasing.”
Accumulation of flow debt means that the WIP average age will increase, violating the Little’s Law assumption. As the level of flow debt increases, your system becomes more unpredictable and your estimates become more inaccurate.
What process scenarios lead to Kanban flow debt?
Frequent expedited/emergency tasks
Kanban teams using Classes of Service generally have an emergency/expedite class. The policies of this class often allow WIP limits for each stage of the process to be violated for one emergency task at a time.
When an emergency task is pulled into the process and no team members are available to work on it immediately, someone must stop working on a standard task. This artificially ages the standard task in favour of the emergency task and creates a flow debt.
The flow debt repayment cost of longer cycle times for the standard tasks can be worth the benefit for severe emergencies. However, it is important to not fall into the trap of making all high priority tasks emergencies.
Lack of pull policies in place
Tasks should be processed in the order that they arrive. If this policy is not implemented, the team naturally focuses on high priority tasks in progress. Eventually, routine, low-priority and maintenance tasks in progress get neglected and ignored. Low priority tasks have a way of becoming high priority problems when they are left alone for too long – make sure they are worked on at the same rate as the rest of the tasks.
Tasks that are blocked from moving from one process state to the next can also cause accumulation of Kanban flow debt. Adopt a process of early feedback about impediments and potential blockers – Kanban meetings are a great way to check in with your team and other stakeholders. Ensure that your team understand the importance of being proactive. Blockers which are identified early in the process can be taken care before flow debt begins to accumulate.
It is normal for a team to have a natural ebb and flow as some tasks are completed faster than others. Small amounts of flow debt occurring on a short term basis are not causes for alarm. However, it’s important to keep track of how long tasks spend in the process. If the age of your oldest tasks are getting further and further away from your average cycle time, it’s time to take a closer look at your process and policies.
Have you experienced accumulating flow debt? What was the cause of that situation? How did you resolve it? Tell us about your experience in the comments!
Meet the Author
Sonya Siderova is an independent consultant who helps organisations deliver successful projects as a Product Manager and Agile Coach. She is a proud mother of a daughter and a son, and enjoys good food and heavyweight boxing championships. Sonya is a regular blogger and founder at Nave.
Many product managers appreciate the benefits of Kanban, but don’t know how best to prioritize tasks. How do we han… https://t.co/Zi9tBiItL4Follow
High flow efficiency is vital to sustaining a scalable, productive business. Learn how you can calculate, analyze a… https://t.co/OysMenyLeRFollow
Two Kanban roles, Service Request Manager and Service Delivery Manager have emerged to equip teams with important d… https://t.co/X2zVYhq1oeFollow
To make your processes more efficient, first you need to identify where you are falling behind. Learn how to recogn… https://t.co/UbIDPd3tfwFollow
Are long cycle times holding your business back? By following these tips and integrating data-driven analytics into… https://t.co/Xgxmq6CU6PFollow
The main flow metrics in Kanban let you monitor your productivity and give you the information to make data-driven… https://t.co/ndLIyWqNqDFollow
Large teams and complex projects face a common issue – the Kanban board becomes cluttered and hard to read. Learn h… https://t.co/auLny9yNnEFollow
How did supermarket restocking techniques revolutionize project management? Learn the history of Kanban and how it… https://t.co/WZUw8z8UqwFollow
Optimizing workflow efficiency is often at the forefront of project managers’ minds, but eliminating idle time isn’… https://t.co/ZmEK020Yu0Follow
To improve workflows, first you must understand how to identify problem areas. Learn how to recognise the most comm… https://t.co/1cpIY9wVOJFollow
Wasteful activities that add no value to your business, also called Muda, can have a detrimental effect on your pro… https://t.co/RG5ZTG3raqFollow
Though it's easy to focus on less complex tasks first, neglecting work in progress can put your team at immense ris… https://t.co/wi4QFY03AjFollow
The Kanban Method focuses on making iterative, incremental changes to workflows to increase efficiency and producti… https://t.co/He4AtSVJXzFollow
Two Kanban roles, Service Request Manager and Service Delivery Manager have emerged to equip teams with important d… https://t.co/N6uQzpDQLhFollow
What makes the difference between an effective daily standup and one that just wastes your team’s time? Our short g… https://t.co/IJU8u5Let3Follow
Are you always short on time and on budget, even though your team is motivated and skilled? Learn how our team at N… https://t.co/f5PKT4gdq1Follow
In this infographic, we’ll be explaining how to identify bottlenecks and stabilize your workflow with the cumulativ… https://t.co/IyNAPj0C2UFollow
When making forecasts, it is impossible to escape uncertainty. Monte Carlo simulation uses permutation of numbers t… https://t.co/1yB4d3nIaXFollow
Lasting change happens in increments, over time. Learn how applying Kaizen principles brings continuous improvement… https://t.co/D6hRs2LfWmFollow