Should Radio Personalities Rehearse Their Shows?

Want to show a jock the importance of rehearsals and show prep?  Show them this video:

Keep in mind the following:

1) He set up his video recorder (probably his phone) hooked it into the air feed and recorded this bit, so he knew it was coming.

2) He didn't stumble, stammer or hesitate.  He knew his lines and delivered them perfectly.  How often to do think he rehearsed?

3) Biggest point - he had only ONE chance to do this right.  And he did.

One of the most celebrated personalities on a music formatted radio station in the US.  I'd love to know how and when he rehearses this bits.