Is it from you management homework or what?
This is one of those loaded questions which doesn't have a perfect answer. So its more like "It depends".
If you ask a manufacturing/assembly line person he will tell you perfection is required because even a simplest, unimportant thing can cause issues later. As elucidated by the example above.
But..then there are things like software engineering where things go wrong no matter the amount of smallest details you cover. There is no perfection in software because there are always scenarios you haven't thought of. That's why software engineering tends to have rollback plans, disaster recoveries, bug bounties etc.
The interesting thing comes when people try to apply six sigma or other manufacturing "best practices" to software, it is always a disaster. Same goes for vice-versa.