You actually have to ensure that someone isn't just checking boxes the tests passed and the tests actually passed. I worked for a regional ISP that had a major

You actually have to ensure that someone isn't just checking boxes the tests passed and the tests actually passed. I worked for a regional ISP that had a major outage when the redundant fiber provided by the telephone company was cut in one place triggering a full loss of connectivity. It also caused a massive 911 outage for 200,000 people as it isolated the 911 center from the city core. Turns out the phone company didn't connect one side of the ring topology even though they certified they did. Needless to say lawsuits abounded.