Seth Godin

On meeting spec -

https://www.linkedin.com/pulse/guest-series-interview-1-seth-godin-power-meeting-spec-juliet-funt/

Point: Simply, does it meet spec? If it does, you are done. If you defined 'spec' well, you need to do no more, no less. Exceeding spec is a form of procrastination, prevents us from getting more important things done.