He has a lot of detractors, but JT The Brick at least tells his listeners to be prepared and have their crap together--and be awake and energetic--for their call. Those who aren't quickly get cut off and a recording of him saying TIIIIIIIIIIIIIME! is played (thought it sounds more like TOWWWWWWWWWWWWWN!)
You're right, you wait on line for 20 min and when the time comes you don't have much of anything to offer.
Then there's the old:
HOWIE: "We have time to squeeze one more caller in"
CALLER: "Uh....uh..."
HOWIE" "Turn your radio down please--is it off? OK, go ahead. We're up against a hard
break, you have 20 seconds."
CALLER: "Uh...um, great show uh Howie. First time caller, uh long time listener. So um... you were...
when it um...comes to.."
HOWIE: "Sorry, we're out of time." (gives phone number out again). "I'm Howie Carr."
(then again I have heard callers use their 20 seconds and make the point quickly and
successfully)