Manufacturing Breakthrough Blog

The Wasteful Art of Bad Multitasking

Wednesday December 23, 2015


In my last post I presented some of the reasons that the Critical Path Method (CPM) for managing projects has such dreadful completion rates.  We discussed two of the reasons, referred to as the Student Syndrome and Parkinson’s Law, but are there other reasons?  The answer is yes and in today’s post, we will discuss these other reasons.


The Critical Path Method (CPM)

Another significant problem related to CPM is that in many project based companies, leadership initiates projects without considering the capacity of the organization to complete the work.  Leadership also mistakenly assumes that the sooner a project is initiated, the sooner it will be completed.  As a result, perhaps the most devastating problem of all associated with project completion occurs……bad multitasking!  But wait a minute….I thought we’d all been taught for years that multitasking is a good thing?  Good multitasking is good, but bad multitasking is not.

Bad multitasking happens when resources are forced to work on multiple project activities at the same time. Many people believe (especially in leadership positions) that multitasking is a good thing because it increases efficiency since everyone is “busy” all of the time.  If you’ve ever to read The Goal by Eli Goldratt [2] (if you haven’t, you should), you might remember how focusing on local activities actually damaged the overall system performance.  You may also recall how Goldratt used his robot example whereby running the robots continuously, efficiency did improve, but at the expense of creating mountains of excess inventory.  The negative impact of bad multitasking in a project management environment is much, much worse.  Let’s look at an example.



Suppose you have three projects that you are assigned to work on and in each project you have estimated that you have 2 weeks (10 days) of work on each project for the tasks assigned to you.  Assuming Murphy didn’t strike, if you started and finished Project 1 without stopping or working on any other project, it would be done in 10 days.  Ten days because that’s what you told everyone it would take (Parkinson’s Law). But having laid it out like this, if all three projects were scheduled to start on the same day, then Project 1 would be on time at 10 days, Project 2 would be done in 20 days, but would be 10 days late and Project 3 would be done in 30 days but would be 20 days late.

Likewise for Projects 2 and 3, assuming no other interruptions, each would take 10 days to complete for a total time to complete the three projects of 30 days.  But CPM doesn’t usually work like this in a multi-project environment.  Because there are probably three different project managers, each one is most likely telling you (or maybe even screaming at you) that they need you to show progress on their project (remember, projects are typically measured by % of tasks complete versus some due date).  You want to satisfy all three managers, so you decide to split your time between the three projects (i.e. you’re guilty of bad multi-tasking).

Bad Multitasking Example 2 

By using bad multitasking, look what’s happened to the time to complete each individual project.  Without bad multi-tasking each project took only 10 days to complete and 30 days to complete all three.  With bad multi-tasking Project 1 took 28 days, Project 2 took 29 days and Project 3 took 30 days, again with all of them finished in 30 days.

Both methods completed all three projects in 30 days, but which set of results do you think your leadership would prefer?  Having two projects done in 20 days and the third one at the 30 day mark or the results of bad multitasking?  Keep in mind also, that when you are guilty of bad multitasking there is also time required to get re-acquainted with each project so the multi-tasking times will actually be considerably longer.  In fact, some studies have shown that tasks often take 2-3 times their estimated duration when multi-tasking occurs. So let’s summarize what we’ve learned before we move on.

  • We’ve learned that task time estimates for tasks are artificially lengthened as a protective measure against Murphy and all of the negative baggage he brings to the party.
  • We’ve learned that even though this safety is built in, it is wasted because of the Student Syndrome and Parkinson’s Law.
  • And finally we’ve learned how devastating bad multi-tasking can be to the completion rate of projects.


Next Time

In my next post we’ll complete our discussion on the CPM method and begin our discussion on an alternative method, Critical Chain Project Management.  As always, if you have any questions or comments about any of my posts, leave me a message and I will respond. 

I wish you all a happy holiday!

Bob Sproull


  1. Goldratt, Eliyahu M. Critical Chain, (North River Press, MA, 2002)
  2. Goldratt, Eliyahu M. and Jeff Cox The Goal, (North River Press, MA, 1984)

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