In fact, faces-config.xml is always included. You would only need to use this stanza to denote *other* files that have faces configuration.
Joined: Jan 26, 2006
I think in most trivial apps faces-config.xml is used as the conf file. But, I see the DD element irrespective of any ither configuration file in almost all JSF Web Apps. I think it has become a common practive to include this element in the DD file.