Goldratt’s Rules of Flow: Chapter 24 – “Buffer Management”

[If you haven’t read the original version of The Goal – it’s the original, the classic. Here’s a chapter-by-chapter video summary, and a <60 second summary too.][Click here for a video summary of Rules of Flow.]

Marc attends Professor Rick Silver’s Executive MBA course on Rules of Flow. The class discusses how to allocate times to buffers – usually 1/3 is a good rule of thumb. They discuss the ‘fever’ chart to track project timeliness. Marc realizes that a lot of the minutiae he tracks from his team has now become busywork as he has cut the number of projects and increased the flow of WIP.

Best Quotes, Writing (Pages 143 – 153)

“If your due dates are not set in stone, then most likely removing the obstacles to your projects’ flow is all you need to focus on. But,” Rick raises his index finger to emphasize what he is about to say next, “if meeting the due dates is key in your line of work, then in addition to managing the flow you also need to take precautions to ensure you meet your deadlines.” – Page 143

“A good rule of thumb is to take a third of your estimated time for the project and use it as your buffer.” Rick to the class, Page 144.

“You may need to ask a few questions but sooner or later they’ll tell you that their estimates consist of the actual time they think it will take them to perform their task, plus safety they believe they need to guard against issues that may come up.” Rick to the class on creating psychological safety for teams to properly estimate due dates, Page 145.

“When people approach their manager asking for more time, the first thing the manager should do is grant them the time they asked for.” Professor Rick Silver to the class, Page 146.

Kiara says, “So, after we grant the time people asked for, we need to look into what caused the delay, and if we find out that people did not adhere to the expected behaviors they should beheld accountable for it.” Page 147

“Another thing that managers sometimes find,” Rick continues, “is a person or other resource that is busy to the extent that queues of work start to pile up in front of them.” Page 148

  • This is similar to how Alex Rogo finds that heat treatment is a constraint in the original Goldratt text for The Goal in Chapter 18.
  • In that book, product inventory accumulates in front of an oven, which the team had been ignoring. They had falsely assumed that the NCX-10, a robot, was the constraint.

“This is a project status chart, or a ‘fever chart’ as we sometimes call it. As you can see, as long as you complete a larger percent of the project relative to the percentage of buffer you consume, you’re in the green and everything is fine.” Rick Silver to the class, Page 149

“Whenever someone approaches us asking for additional time, we grant it to them but we look into what caused the delay and respond in accordance to what we find out.” Rick to the class, Page 150.

“A word of caution. If you don’t properly control your WIP, don’t bother with monitoring the buffers – you will consume them for sure.” Rick to the class, Page 151.

“When someone messes up in a way that causes a considerable delay, we dig deeper and look into what caused the delay in the project. We ended up adding more and more details to our status reports to make sure we don’t overlook them again. Over time we went into finer and finer detail and by now the lists we cover in our status reports are rather long.” Marc shares the status of the elaborate paperwork required of his teams to the class, Page 151 – 152.

“Letting to of checking the status of these many details shouldn’t be taken lightly. He has been relying on these status reports to hold his people accountable for as long as he can remember. But does he really need them anymore? Most of the screwups were a result of the chaos they operated in, but now that they are avoiding a lot of the bad multitasking and having full-kits, people can concentrate and they make fewer mistakes.” Marc reflects on changes he can make, Page 152.

“After the past few months they were used to his unorthodox ideas. It’ll be fine.” Marc closes his thoughts and the chapter, Page 153.

About flybrand1976

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