If you lived in Florida, you would have heard Gene Deckeroff on F.S.U. football, basketball, baseball, two arena football teams and the Tampa Bay Buccaneers. He also sold the advertising, negotiated the TV and radio contracts plus managed to start his own production company while working as executive producer for two coaches shows.
I think the more work you're afforded, the more your talent builds and thus you become highly coveted. You work hard to hone your craft and build momentum earning you the chance to do (and earn) more. To quote an article in this months Sports Illustrated and something the overnight guys on Fox Sports Radio have mentioned..."It is what it is" ;D