To me this advice belongs and any design effort, there seems to be a constant pursuit of the absolute and everyone seems to be trying to find some sort of mathematical perfection. Seeking perfection or the absolute all the time seems to me to destroy the space needed for innovation. Once in stone evolution becomes hard or usually stops. Keeping in a prototyping mind sets allows you to continuous improve what you have. There is nothing wrong with letting a prototype into the world when its ready. Take the risk set if free when its still malleable and you find build a great product.