Theory of Constraints Handbook - James Cox Iii [13]
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An hour lost on the bottleneck is an hour lost on the entire system; an hour gained on a non-bottleneck is a mirage.
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We now recognize that the vast majority of the elements of a system are non-constraints. We also recognize that for non-constraints more might not be better but worse. So, what must be the unavoidable result of following the prevailing notion that more is better? The number one reason for not doing what should be done is doing what should not be done.
We don’t have a choice but to define focus more narrowly: do what should be done AND don’t do what should not be done.
Measurements
According to cost accounting, when operations produce they absorb cost into the inventory and this cost absorption is interpreted as increasing profit. In other words, the cost-accounting concept encourages any production, even on a non-bottleneck, even if it is above the threshold. It is no wonder then that the first implementations of TOC clashed with cost accounting. It was mandatory to develop an alternative. Almost immediately, Throughput Accounting (TA)—a system based on simple definitions of Throughput (T), Inventory (I), and Operating Expense (OE)—was proposed alongside the explanation of the difference2 between the Cost World and the Throughput World.
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Tell me how you measure me and I will tell you how I will behave.
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The Goal and The Race
Rapidly, the realization of the crucial impact of bottlenecks gave rise to a collection of actions that were previously deemed inefficient and now were recognized as the most important actions to be taken. “What should be done” now took on new meaning.
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A novel about manufacturing? We don’t even know what shelf to put it on. It will never work.
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No less important was the recognition that it is impractical to monitor each non-bottleneck separately and therefore constructing and implementing a system to prevent the overproduction of non-bottlenecks was essential (Drum-Buffer-Rope [DBR] and Buffer Management [BM]). The understanding of “What should not be done” was even more tantalizing.
This body of knowledge was captured in detail in The Goal (Goldratt and Cox, 1984) and conceptually explained in The Race (Goldratt and Fox, 1986).
Other Environments
The clear logic, the simplicity, and the rapid results that TOC provided in production caused other environments to try to implement the same. Unfortunately, some of them were so different that even the constraint was different in nature. The constraint in project environments is not bottlenecks but the critical path (or, more accurately, the critical chain). The constraint in distribution has nothing to do with bottlenecks. It is either cash (wholesalers) or the number of clients that enter the shop (retail). The term bottleneck started to be misleading; it had to be replaced with the broader term constraint. That was the time (1987) when the term Theory of Constraints3 was coined and a precise verbalization of the focusing process was offered—the five focusing steps.
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When you are good with a hammer everything looks like a nail.
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That was not enough. Applications for proper guidance of the non-constraints in distribution4 (blocking the tendency to push the merchandise downstream [replenishment to daily consumption]) and in project environments (blocking the tendency to buffer the individual tasks [Critical Chain Project Management]5) had to be developed in full.
The Thinking Processes6
Only when environments other than production had been dealt with using TOC did the paradigm shift dictated by the narrower definition of focus fully surface. To focus properly, the following questions had to be answered: How do we identify the constraint? What are the decisions that will lead to better exploitation? How do we determine the proper way to subordinate the non-constraints to the above decision? And how do we reveal more effective ways to elevate the constraint? It became apparent that even the best available