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TOC in Project Management · Lesson 2 of 6

The damage of bad multitasking

Switching between projects feels productive. Measure it, and it turns out to stretch every project, waste capacity and send work downstream in waves.

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A simple experiment

Two projects, P1 and P2. Each needs the same 20 small steps, and one person does them all.

  • Round 1: multitask. Work a few steps on P1, switch to P2, switch back, as priorities demand. Every switch needs a moment to find your place again.
  • Round 2: one at a time. Finish P1, then do P2.

Each step takes the same time in both rounds. Yet in round 1, both projects finish at about 40 seconds. In round 2, P1 is done at about 20 seconds, half the time, and P2 still finishes no later than before.

Pause and think: in round 1, nobody worked slower. Where did the extra time go?

  • Nowhere: it was the same total work
  • Into set-ups at every switch, and into each project waiting while the other was being worked on
  • Into the stopwatch
  • Into longer steps

Two losses. Every switch costs a set-up: finding your place, remembering where you were. And while you work on one project, the other just waits, so both take as long as the slower total. The work didn’t grow; the elapsed time did.

The four damages of bad multitasking

Look at the elapsed time of any task done while multitasking. It is made up of productive time, set-up time at each restart, and no-work time while the task waits its turn. Four damages follow:

  1. Effort stays the same, but elapsed time expands. Each task, and so each project, takes far longer than its work content.
  2. Lead times grow. Every project in the system slows down, not just the one that got interrupted.
  3. Capacity is lost. Set-ups and restarts are time no one gets back. The more switching, the less real work the team delivers.
  4. Work moves in waves. Projects finish together in bursts instead of a steady flow, so the next team gets flooded, starts multitasking too, and the damage spreads.

Why does it happen?

Nobody chooses bad multitasking on purpose. It comes from rational local decisions: every project manager pushes their own project, every customer escalation jumps the queue, and a shared expert tries to keep everyone happy by giving everyone a little. Starting projects early “to be safe” makes it worse: more open projects means more to switch between.

This is not the same as doing several things at once when one of them is waiting, like sending an email while a test runs. Bad multitasking is switching away from work that could have continued.

Check your understanding

Answer all five. Get four right to complete the lesson.

1. In the two-project experiment, switching makes the first project finish…

  • Sooner
  • At the same time
  • Much later: about twice as late
  • It never finishes

About 40 seconds instead of 20.

2. The elapsed time of a task done while multitasking includes…

  • Productive time, set-up time and no-work time
  • Only productive time
  • Only set-up time
  • Overtime

Only the first one moves the project forward.

3. Which is NOT a damage of bad multitasking?

  • Longer lead times
  • Lost capacity
  • Work moving in waves
  • Lower effort per task

The effort stays the same; the elapsed time grows.

4. “Work moves in waves” means…

  • Teams work in shifts
  • Projects finish together in bursts, flooding the next team
  • Work only happens in summer
  • Tasks are always late

Feast then famine, and the next team starts multitasking too.

5. Bad multitasking is…

  • Doing something useful while waiting for a test
  • Working on one project at a time
  • Switching away from work that could have continued
  • Any teamwork

Switching while the current task could still progress is what does the damage.