Faulty components can be spotted during the development phase of your signage project, giving manufacturers time to correct any problems before the parts are installed on further sites. At worst, they may be spotted in the early stages of implementation.
Unethical companies may well force a faulty or badly-fitting component into place, perhaps even using a hammer, sign-off the job and wait for the component to fail (inevitably before the end of its design life). They will then charge you again to rectify the damage.
Only financially well established sign companies are able to offer intelligent reporting, as they must have the financial capability to support any delay in project completion incurred by the faulty components.