I probably sit in the middle, where I see the value of good signs (and good design in general) to properly guide the users so they don't have to rely on heurist

I probably sit in the middle, where I see the value of good signs (and good design in general) to properly guide the users so they don't have to rely on heuristics and "blind" fallbacks. In particular for airports where dealing with huge influx of users at peak time is critical. On the other hand, for many people, having to talk to a security guard and move to the lane on the other side is a non-event, and they might have tried to talk to the guard even if there was absolutely no need for it, if they felt it wouldn't be an issue for the guard (not too busy, looks bored etc.). Efficiency could be super low on their priority list, if it wasn't they'd be paying a lot more attention to the signage in the first place.