You already know what a bad rack looks like.
It looks like a Wednesday afternoon.
The site engineer rings. Labels don't match the schematic. He's spent two hours tracing what should have been a five minute patch. He can't finish today. You start moving people.
By Thursday, he's found something worse. An internal cable terminated wrong, cut too short to re-terminate. To replace it, someone has to unpick the dressing, lace a new cable run in through everything that's already been tidied, and put it back together. By Friday, you've put a second engineer on it, pulled off another job, which now slips too.
By next Wednesday, that rack works.
Then at handover, the client looks at it just a second too long. It's not as neat as it should be. The meeting is colder than it should be. You walk out already thinking about how to phrase the next quote.
Now multiply that across every rack you'll ship this year.