The subject of running shorter trains has come up in the Worldwide Railfan forum. Back around the late 1960's the Reading announced a service featuring short trains (carload, not intermodal) for multi-car shipments from one shipper to one consignee, operating directly from origin to destination with no intermediate yarding, and I believe possibly with crews reduced from the 5-man standard of the time. (I think it was at the same time that the green-and yellow paint scheme for locomotives was introduced.) It got a big play in Railway Age when it started, but I never saw any follow-up stories. Anyone know how it worked out in practice?
It worked as you described... door to door on-call (two hours notice) service.
Here's a short video about it.