By Suzanne Johnson, MBA, CAPM, CSM, CSPO


What do these activities have in common?

  • Designing an expansion for an urban office building,
  • Creating a new logo for a sports brand,
  • Analyzing traffic flow through some proposed road construction,
  • Interpreting financial data for an upcoming shareholder's meeting,
  • Testing the next software release.

Each requires intellect and focus to transform information and knowledge into a product orservice. The term “knowledge worker” was first coined by Peter Drucker in his book, The Landmarks of Tomorrow (1959). We all have knowledge workers on our teams; in fact, project managers are knowledge workers. Knowledge work is complex, unpredictable and variable. How do we best manage these constrained resources?

Knowledge work flows. It is not measured in units but rather in time and volume. Think of flow as a metaphor: movement, cascading, one-way, rhythmic, pooling behind obstacles. Most of us know that "multi-tasking" is a misnomer. Our brains cannot perform more than one function at a time. What is the cost of multi-tasking? What is the cost of interrupting the flow of knowledge work?

In his book, Quality Software Management: Systems Thinking (1991), Gerald Weinberg proposed a rule of thumb to calculate the waste caused by project switching. This applies to any knowledge worker switching from one project to another, or from one context or task to another. The chart below depicts the loss of productive project time as a worker attempts to multi-task.


Try this for yourself in a simple five-minute game: The Myth of Multi-tasking Test by Dave Crenshaw. As stated in the video, the costs of task switching are time, quality, and stress. There are also financial costs which we will explore in next month’s article. As a project manager, it is critically important to protect team members from costly interruptions whenever possible.

I’m interested in how you help your teams stay focused and productive. You can reach me at

Thanks to Kevin Callahan for his expertise in this area. Kevin is a great local resource as a speaker, coach, trainer, facilitator, and consultant. Kevin's LinkedIn Profile