Well if you look around the net you will find that the sites with the highest pagerank, most readers, most comments (normally) , and content will be Blogs that have a lot of posting. Here’s another way to think about it. : The more posts (content) on your site, the more content that will get indexed, meaning the more traffic that is possible to come from search engines. It will also give reason for your readers to return. So post as much good quality content as you can.