Tom Madden wrote:

<snip> I don't have a layout but occasionally operate on the layouts of
friends. It's always bothered me that, at the end of a session, every
piece of rolling stock on the layout has been dealt with. Even cars that
are spotted where they were when the evening started had to be moved at
some point. No allowance for stored cars on the visible portion of the
layout.

I recall the article by Douglas Smith on card operation [The latest word
from Doug on card operations, Model Railroader, December 1961
<http://index.mrmag.com/tm.exe?opt=I&MAG=MR&MO=12&YR=1961&output=3&sort=\;
3> page 52] that the sequence was to leave a car stay in place at the
customer's spot for at least one sequence of the local freight passing
through a town with the sequence being drop-off, load or unload, and
then pick-up. No doubt methods to operate layouts are more complex
today, but this simple step to allow time for a car to be either loaded
or unloaded should be incorporated into any operating scheme.

Bob Witt
Indianapolis, Indiana