It depends on what you're doing with your website, but we definitely recommend you a plan for this.Content is critical for optimization and "fresh" or new content is an important factor for ranking.

If you have a small business brochure website you might probably want to update twice a year some pages on your website, you might also have a page to display the latest news on your website and you can add a couple of notes once a month or every two months if you want.

For e-commerce or database websites you might update or add content more frequently, those kind of websites are build to have those changes as need it. In any case if you're doing optimization, you might want to talk with our optimization people about the importance of getting new information on your website and what will be the best way to do it without having problems with the code and content to optimize your website.