I agree...but you have to take into account host egos...they each think they have a "unique" take. If it's a big topic, they think no one can cover it like they can.
I still have to emphasize, however, that momentum builds on a topic during the day. The folks that don't get to expound in the AM will be the first ones on the phone in the PM.
Also...the audiences are not as similar as you might think.