So let's say you decided to update the content on a page on your web site, the content is super out dated and needs a major revamp. When you update the content, it doesn't mean you need to put that new content on a new URL, you can just update the content on the existing URL. In fact, Google recommends it.
Via THE OFFICIAL ANDREASCY
Adding content to older pages lives by Google's QDF (Quality Deserves Freshness) rule and reduces quantity in favor of quality. That last part, the reduction of quantity in favor of quality, seems to be motivating Google's latest algorithm changes (to the extent anyone can understand why Google does anything.Â