The exception to the general rules were most often to assist switching situations enroute. A baggage car or pullman at the rear might be aimed to be set off along the way.
With diesels and AC, the rear of a train is not necessarily as desirable as it once was either.
Reading had a strreamlined steam train that ran from Philly to someplace, maybe Atlanic City called the crusader. It had a streamlined obervation car at each end and the tender of the streamlined steamer had an overhang to bleend in with the end of the observation. the purpose was to so they did not have to turn the train, only the loco, and could still have a stainless streamliner with an obs at the end in both directions. I gather the trip was just a few hours or so, and the train made a round trip.
