Saturday, April 18, 2020

Essential Lean - Waste Red Flags


We need to find out the sources of waste, but that requires a very good and close observation of the overall process. Some wastes, tough are important, are difficult to identify. For example:
  • It is difficult to find that you have a lot of extra features or junk stories in your product. 
  • It is difficult to find that you have a lot of hidden work (for example product parts that are hard to read or are hard to change because of the technical debt) 
Some other sources of waste are easier to detect, and are induced by most of the others (see "Avalanche effect"):
  • Waiting
  • Defects


This means that, although we could successfully use Waiting and Defects wastes as red flags, finally we need to identify and eliminate the root causes. We should also remember that we cannot reduce the Lean goal of avoiding waste only to these two sources. Waiting is the main subject for the methods that use a visual control of the work. However, if something is harder to draw, it does not means that it is less important. There is no generic ranking between the main sources of waste and their impact is different from one context situation to another.

Essential Lean Series

Read first: Principles of lean thinking (by Mary Poppendieck)     

Essentializing Lean - essay
Essential Lean - Red Flags

Essential Lean - Waste avalanche effect


Avalanche effect 


Many sources of waste will induce others, and it is hard to tell where this chain reaction ends, as it causes an "avalanche effect".  The following are some examples.
 

Overproduction - Extra features and junk stories increase the product and the release scope amounting to a bigger inventory.  Big inventory - A big work in progress increases work complexity. A higher complexity for both problem and solution results in more defects. More defects introduce more unexpected interruptions of the work in progress and that produces more waiting. Waiting ...  

Vicious circle

 

An even worse situation is a vicious circle effect between wastes. If wastes are not avoided, the difficulties not only persist but will increase in a never-ending spiral.    


Task switching affects people's focus and that increases the number of defects. More defects amount to more unexpected interruptions, which results in more waiting. With more waiting, the delivery is delayed, and the target business changes more than we previously expected. With this extra time, we receive more change requests that will increase the release and the product scope (inventory). With a bigger inventory, task switching increases: we cannot good enough slice the work inside a release, we can't say that something is done and the work for different things will interfere.         

A situation where the vicious circle could be even faster occurs when two wastes are directly feeding each other.  



Task switching reduced focus and that in turn increases the number of defects. More defects amount to more unexpected interruptions, which in turn result in more task switching.

A lesson to be learned 


We cannot disregard any important source of waste since each one creates and feeds other wastes.



Essential Lean Series

Read first: Principles of lean thinking (by Mary Poppendieck)     

Essentializing Lean - essay