Do Just One Thing

1 minute read

A short post on the merits of doing just one thing at a time, extracted mostly from Jeff Sutherland’s Scrum book, and some supporting / referenced materials.

Multi-tasking is a myth. Humans cannot multi-task. Stop trying to multi-task.

Our brains cannot do two things at the exact same time. We can think about two things (in different lobes of the brain), but to actually process those things, our brain switches back and forth serially between each.

The same logic can be applied to working on multiple projects / problems or discussions / conversations. Juggling introduces an overhead referred to as ‘Loss to context-switching’.

Loss to context-switching can be thought of as the effort expended to reposition yourself into the last context of the project / train of thought that you switch to.

In software development, this might be re-familiarising yourself with the project domain, the programming language, the story requirements etc. This is wasted effort.

There has been much research into waste within the software industry and we can quantify it. Take a look at the following table which appears in Quality Software Management: System Thinking by Gerald Weinberg.

Number of simultaneous projects Percent of time available per project Loss to context-switching
1 100% 0%
2 40% 20%
3 20% 40%
4 10% 60%
5 5% 75%

Madness right?

If you are hopping between five different projects, then you are only devoting 5% per project, the waste due to context-switching is 75%. In that scenario, for each hop, you are wasting 20% of effort.

This doesn’t only apply to software projects, but instead, anything that requires a specific state of mental awareness that when lost, can take minutes, or hours to reacquire. Timeboxing, or calendar-blocking as it’s also know, can be a neat tool here. Three or four two-hour blocks of ‘Do Not Disturb’ time to support your focused work.

Pick one thing. Do it, and do it well.