Database instance for SCCM 2012 and WSUS on a single primary site server

Question

I am going to install SCCM 2012 and its SQL database on a single physical server. This is going to be a single primary site server. The default SQL instance will be dedicated to SCCM 2012 with no other named instances to be added on the SQL server down
the road.
During the WSUS server role installation, there is the Database Options page asking for using (1) Windows Internal Database, (2) existing db server on this computer, or (3) an external db server.
Since SCCM 2012 doesn't share db instance with others, how should I handle the WSUS db that's going to be hosted on the same SCCM/SQL physical server? Do I really need to create a separate SQL instance just for the WSUS db?
Thanks and regards. 

Answer 1

Even though you can do it, it is the best practice to have SCCM 2012 and WSUS installed on separate instances.
http://technet.microsoft.com/en-us/library/hh692394
When the Configuration Manager and WSUS databases use the same SQL Server and share the same instance of SQL Server, you cannot easily determine the resource usage between the two applications. When you use a different SQL Server instance
for Configuration Manager and WSUS, it is easier to troubleshoot and diagnose resource usage issues that might occur for each application.