Nice article -- I think the first thing one would tend to apply it to in a startup context is a startup as a whole, but I believe in a successful startup quitting often, and at the right time is critically important. It seems foregone when going into something new that your assumptions will be wrong a lot of the time. Figuring out when to give up on some strategy, despite having invested time in it and go to try the ones that are working seems to be one of the rules of engagement.