Here is my rule of thumb of building and maintaining momentum: it takes six months to really have the fruits of your labor in doing PR pay off. I am talking about the process of developing your message, developing your media and analysts strategy, creating and selling your news, and then having a backlog of quality articles and analysts reports you can post to your web site and see that your company really matters.
If you depart from your PR efforts, your momentum goes away. You fall off the radar. You lose your rankings on the search engines. Your message become outdated. You don’t remain relevant. And you stand the chance of being displaced.