actually there are no solid rules about this, but through out my experience, especially in software websites, after 5 days of not writing a new or refreshing your content, you will appear less on search engines. I noticed it through out using Google Analytic.
What I mean is : For example, there are websites that deal with software, there is a big competition to appear first in Google, so they tried to keep the same link for the page ( lets say a page that talks about Google Chrome ) and spread it on the web and whenever a new edition is released they will only refresh the content and keep the same link and they will spread it again. To conclude : 1. They keep the same link to the page and spread it on the web. 2. Whenever a new edition is released they will just refresh the content and spread the page again. 3. by this way they will earn a huge back links to the page and maybe by time it will earn a good page rank and appear first in Google. 4. This is good and will save time by redirection command to the .htaccess or any other way of redirection. Regards
Unique content plays major role in ranking. By using unique content you can get rank in search engine in weeks.