Just an observation: in the late 70s I worked at the Kokomo Transmission Plant. There was a large area where they staged the loaded racks of finished transmissions waiting to be shipped out to the assembly plants. Sometimes this area was pretty empty, so the transmissions would be shipped out very soon after completion. Other times this area was completely full with racks of transmissions back against the wall, completely blocked in. In this case the recently finished transmission still went out quickly, but sooner or later the transmissions that were back against the wall finally went out to assembly plants. The production date on them would be much earlier than the assembly date on the car. First in first out was probably a goal, but many times the cyclic nature of the industry got in the way.