Cutting off the line on an intermittent set would be a catastrophically bad idea as people would just start unofficial lines. They all could have been b2b but it does not look like that was the caseThis comment doesn't really make sense. If the number of people hasn't exceeded how much time they have left to greet, why should any lines be cut off? If people are willing to wait in such a line, that is their choice. Cutting off the line prematurely would be far worse.
As long and hot as everything was, at least they were all fair and well organized lines. Kudos to them for doing as much as they could to keep things moving. Short of having these characters out more often (which seems to be a losing battle), there's not much else they could have done differently for this event itself.