Good question. I would start with just mains and sub (actually I would be tempted to start with just sub) since in general as you add more speakers the ups and downs will be smaller but there will be more of them.
I think Mark was just using mains and sub but we should check. Maybe if he runs all 5 speakers the graph won't be so ugly.
In the past I don't think there was much LF on the center and surrounds but that seems to be changing recently.