One poster made a comment about the requirement for helipads on the top of skyscrapers in Las Vegas which saved 1,000 people at the MGM Casino. If you are going to pull a lot of people off a roof with a helicopter(s) it has to be built for it. If it isn't then it's a case of winching them off one at a time because of TV and satellite aerials, etc.
I cannot imagine a couple of hundred of hot footed people waiting in an orderly line waiting to be picked up by winch. It would be chaos, with three or four hanging on to the one being lifted and it would only end in tragedy for the helicopter crew as well.