...It is epitomized in the paradoxical Toyota proverb, “Stop production so that production never has to stop.” The key to the andon cord is that it brings work to a stop as soon as an uncorrectable quality problem surfaces—which forces it to be investigated. This is one of the most important discoveries of the lean manufacturing movement: you cannot trade quality for time. If you are causing (or missing) quality problems now, the resulting defects will slow you down later. Defects cause a lot of rework, low morale, and customer complaints, all of which slow progress and eat away at valuable resources.
-Eric Ries, The Lean Startup (emphasis mine)