You can fail a project not because you were technically wrong about anything, but because you burned your customer out by taking 6 months instead of 6 weeks to find a viable solution to their problem. Speed is a feature from the perspective of your customers. There is economic value associated with it. Consider your state of mind when you call the HVAC tech to fix your broken condensing on an August afternoon in Texa…
The customer won't be able to tell you "you're going too fast", but he will tell you that stuff break. On top of that, because the rate of shipping new features doesn't necessarily match with the rate of usage of said features the moment you'll find out about it will not happen ASAP but probably sometime later, making it even harder to truly know if going fast is the right thing to do in the moment.