The Metasploit Framework is commercially backed by Rapid 7 and has a very active development community. New vulnerabilities are discovered almost on a daily basis in various systems. For any such newly discovered vulnerability, there's quite a possibility that you get a ready-to-use exploit in the Metasploit Framework. However, in order to keep abreast with the latest vulnerabilities and exploits, it's important to keep the Metasploit Framework updated. You may not need to update the framework on a daily basis (unless you are very actively involved in penetration testing); however, you can target for weekly updates.
The Metasploit Framework offers a simple utility called msfupdate that connects to the respective online repository and fetches the updates: