The frequency in which a site is updated holds some weight with the search engines because it shows that this site is still active and that the information is trying to stay fresh and new. New content is generally a good thing to have for a site's users.
However, there are cases where new content doesn't necessarily matter and a user searching for something may be just looking for the best content and doesn't care whether it was written 10 years ago, or 1 day ago. The answer to their search still remains the same.