Maybe a "new" idea for a "old" subject

[nachoman]

I tend to agree with this concept. There is a local club located in a popular nearby park. The club has viewing windows, and during busy times at the park, the public can look in. Not all of the yard tracks are occupied, but for most visitors the layout is interesting and realistic because there are cars in the yard and at various sidings. People want to look at trains, not train tracks. On the other hand, I have seen people that have huge layouts, and not enough cars to fill the tracks. They may have a yard with 4 tracks and only 4 cars. Technically, from a "number of cars per scale mile of track" standpoint, this may be actually realistic. But, from a modeling perspective, where we recognize distances need to be compressed and the recognition we model trains and not tracks, having fuller tracks than what may be prototypical provides interest. Think of it from a railfan's perspective: Railfans usually hate it when they go out to watch trains and no trains come by, and there are not even many cars in the yard. A railfan is most interested when the yard is full of odd cars and there are plenty of trains moving around. Model railroaders (most of whom are railfans) will have more interest if their railroad represents similar situations.

It also depends on what kind of layout one has. If one has an industrial switching layout, having extra cars around is probably a bad idea. In the real life, those situations probably only ever see cars that are going to or from the local industries. If one has a layout that models portion of a mainline, a responsibility exists to portray the layout as part of a much larger railroad system. Extra cars and parked trains are common along busy mainlines, and could add realism to a layout that doesn't have enough human operators to justify their operational existence. They serve as background to set the illusion of a much larger railroad. But as previously mentioned, it's best to move them around every now and then.