Moving mechanical parts taught me that tolerance is a specification, not a virtue. Digital work hides its tolerances: the form still submits at 300ms of latency, so nobody files the ticket. The users just quietly stop coming.
Now I write the tolerances down before the features: p95 under 400ms, empty-to-first-value under a minute, error copy that names the fix. When the numbers slip, the dashboard says so before a customer does.
A product with declared tolerances feels different to use. I think people can feel it even when they can't name it.