Another lean principle put forward by Hal “has to do with batch sizes of one or single-piece flow.” Hal, as do many Lean and Agile PM proponents, notices that: “Large batch production, whether it's placing concrete, writing software code, doing design, or performing administrative work, misses the opportunity for learning, creates the circumstances for waste, and delays the completion of the project.”
I have already covered the part about very small deliverables (small batch size) in my blog entry on tracking small promises (http://www.projecttimes.com/content/view/180/92/). Unless I misinterpret Hal’s point, I might not have put enough emphasis on the need to deliver them as much as possible on single tasking mode. This is a very important principle to follow, on an individual level, to eliminate waste and accelerate the delivery of your own promises on any given project.
In my blog entry on tracking small promises I reported that, according to research by Goldratt and others, productivity is greatly improved when you deliver in small promises. Doing this reduces the set-up time required for the Last Planner to continue the work to be done after an interruption, thus increasing productivity dramatically. I omitted to talk about the single-tasking technique one can use to further accelerate individual promises delivery. Still, according to Goldratt, although you might work on many tasks in your multi-project environment, you will be more productive if you tackle those tasks one after the other, when possible (usually tasks on different projects that are independent of one another). So Goldratt proposes that you single-task those multi-tasks, that is do one after the other, to save further on task set-up time.
The productivity increases achieved through this single-tasking strategy can be quite impressive. Hal Macomber once wrote about a small experiment one can run in workshops that goes this way:
- Split the workshop participants in pairs, one person executing tasks and the other timing execution time
- Give the following tasks to perform: write three series of characters, namely 1 to 10, a to j, and I to X (roman numbers)
- These tasks must first be performed in parallel, i.e. write 1, a, I, then 2, b, II , etc…while you time the work
- The tasks must then be performed in series, i.e. write 1,2,3,4, etc., then a, b, c, d, etc…..while you time the work.
Try this. You will be amazed by the differences between the two ways of doing these tasks. I have tried that with more than 200 workshop participants up to now. The productivity increases come consistently between 20 to 50 %. If multitasking is this detrimental on such simple tasks as writing series of numbers or letters, imagine what is happening to your projects when you keep switching between more complex tasks, from one independent project task to another, in the hope of accomplishing more during your week.
So Rule number seven of eight of Lean Project Management is Execute your small promises on single-tasking mode.
Rule No. 7 of LPM – Once your deliverables are cut into smaller pieces, deliver them one after the other, as much as possible.
By cutting your project work in smaller pieces/promises, you will save on set-up time each time you are interrupted, thus accelerating delivery. This accelerating effect can be increased furthermore, if you also try to execute these promises, one after the other, this saving an additional amount of set-up time. In a multi-project/multi-tasking environment, the most productive strategy is to single-task, doing these multiple tasks in series, when possible.