Ahh yes, the old "why do we have all these inefficient empty hospital beds???" problem.
On a fundamental level, efficiency and resilience are always a trade-off. A perfectly efficient system also tends to be perfectly brittle! In practice everything needs some buffer.
We shouldn't aim for "as close to 100% efficiency on <metric> as possible," but rather "lowest risk-adjusted expected cost, including mishaps." The latter correctly prices rare events.
On a fundamental level, efficiency and resilience are always a trade-off. A perfectly efficient system also tends to be perfectly brittle! In practice everything needs some buffer.
We shouldn't aim for "as close to 100% efficiency on <metric> as possible," but rather "lowest risk-adjusted expected cost, including mishaps." The latter correctly prices rare events.