ETTO: Efficiency-Thoroughness Trade-Off
The ETTO principle was coined by Erik Hollnagel. It can, in its simplest possible form, be stated as follows: In their daily activities, at work or at leisure, people (and organizations) routinely make a choice between being effective and being thorough, since it rarely is possible to be both at the same time.
It follows from the ETTO principle that it is never possible to maximize efficiency and thoroughness at the same time. Nor can an activity expect to succeed, if there is not a minimum of either.
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Efficiency means that the level of investment or amount of resources used or needed to achieve a stated goal or objective are kept as low as possible.
The appropriate level or amount is determined by the subjective evaluation of what is sufficient to achieve the goal, i.e., good enough to be acceptable by whatever stop rule is applied as well as by external requirements and demands.
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Thoroughness means that an activity is carried out only if the individual or organization is confident that the necessary and sufficient conditions for it exist so that the activity will achieve its objective and not create any unwanted side-effects.
The ETTO fallacy is that people are required to be both efficient and thorough at the same time – or rather to be thorough when with hindsight it was wrong to be efficient!
Erik Hollnagel wrote a book on it: The Etto Principle: Efficiency-Thoroughness Trade-Off: Why Things That Go Right Sometimes Go Wrong