I suppose that a third control segment could be added at the gravel pit, but I think that a third locomotive would be too much for this very small railroad.
The 6.2.1 is meant to be viewed from one side of the railroad, the same view as the perspective view used to illustrate the railroad in the 0294 book. That said, I have always tried to avoid having long stretches of straight track running parallel to the edge of the layout. A long stretch of track running parallel to the edge of the layout causes the viewer to look at not only the train running on that track, but also to look at the edge of the railroad and its relation to the rest of the outside world. This causes the viewer to realize that they are looking at a model train, destroying the visual impact of the layout.
By slightly twisting the railroad on its support platform, the viewer’s eye remains on the train rather than the entire environment. The 6.2.1 has just such a long straight track segment: