Redundancy also adds a lot of complexity, as fail-over mechanisms aren't simple either. That added complexity then turns into additional possible error sources.

A friend of mine builds a component for a satellite system and the FDIR mechanisms need to be chosen very carefully, as adding more fail-safes can actually make the system overall more error prone.

There's an interesting blog post on from AWS about that topic [0]. Turns out adding more fallbacks and fail-safes is actually discouraged there.

[0] https://aws.amazon.com/builders-library/avoiding-fallback-in...