Perfect doesn't exist, but good enough does.
The trouble is that good enough is different for everything. Striking out only every other time you step up to the plate will make you the best player in the history of baseball. But an airbag that deploys correctly 90% of the time? That's a failure.
The line between good enough and failure is often slim. When we define what the former is, we free ourselves from the the Sisyphean pursuit of perfect.