Redundancy and backup systems
Never assume any single component is perfectly reliable. Nature carries two kidneys.
Engineering principle: critical systems should not have single points of failure. Aircraft have redundant hydraulic systems. Data centres have redundant power. Banks have redundant clearing systems. Nature evolved two of most important organs.
The cost is real (you're paying for capacity you mostly don't use). The value shows up in the rare moments when the primary fails. Without backup, those moments are catastrophic.
For operators, redundancy matters wherever the cost of failure is asymmetric (much higher than the cost of redundancy). Key suppliers, key employees, key systems. Single points of failure look efficient until they're not.
Examples in the wild
Companies that source critical inputs from a single supplier eventually get burned. Two suppliers cost slightly more and protect against the supplier crisis that always eventually arrives.
Diversification is redundancy. The reason buy-and-hold portfolios outperform concentrated ones over very long periods is that any single concentrated bet eventually has a bad decade.
Two close friends, two savings accounts, two paths to your goal. The cost is small. The value shows up when the primary fails.
Redundancy and backup systems is one of the mental models we apply through real cases inside the Pareto MBA — a part-time program for professionals who want to think clearly about business.