The rule of thirds here has nothing to do with framing picture in photography even if some metaphoric similarities can be discussed.
The rule of thirds I am thinking about is the potential improvement with Lean.
My own experience tells me that every time a process is analyzed in a lean way, at least 30% of either leadtime, inventory, WIP, or manpower can be saved (sometimes a combination of them).
The process owner or other stakeholders may not allow to cut all of these 30% yet this potential is at hand.
This “rule” seems to be scale independent: even after improving a process and having it operating with 30% less resources, after some time this same process can show again 30% improvement potential.
How can this be possible?
Well, consider a process with people unaware of lean thinking, tools and techniques. Reaping a gain of 30% in this case is generally piece of cake.
After a while, with lean awareness growing, the same people may undertake another critical assessment of the process and discover additional improvement potentials they were unable to see before.
This can go on several times before the process ends in a very lean state and of course, at each iteration, gaining 30% comes at a higher cost.
Another reason is that things change over time:
- new problems arise requiring new solutions
- discipline weakens,
- habits slip back to old ones,
- processes are modified,
- new models are launched,
This rule of thirds may be like the Pareto law, something that happens often, often enough to be called law or rule, even there is no rationale demonstration for it.
Many Lean practitioners I talk with agree with this rule, and if you listen carefully to Dan Jones explanation about what is Lean, you’ll hear:
“Very quickly it’s also freeing up the capacity to deliver a third or more value, from existing resources without additional costs.”