I was talking with an older musician who told me when he was playing full-time back in the 40's and 50's, they'd have two default bridges, the "Sears-Roebuck," which started on the third and wound down (essentially rhythm changes bridge), and the "Montgomery-Ward," which started on the fourth, like A-Train. If someone requested a tune and they didn't quite know the bridge, the leader would call either one of these bridges and improvise a melody over it until the main theme came back around. He said the crowd never caught on.
Duly noted and swiped.