The last layout I had of any size filled two bedrooms of a 3 bedroom town house. It had 50 022 switches, 40 of which were on the main line, and were controlled by the train using the non-derailing function. The switches were wired together in pairs. All I had to do was watch the train run and control the speed. The layout could be configured by switches to run one, two, or three trains. When running one train, it took 22 minutes for the train to complete one circuit.
I had a stepper switch that controlled the 022 switch that allowed the train to go to the second bedroom. The stepper switch was controlled by a control section of straight track. Because of dirt on the wheels of the cars (most likely good ole' dried out Lionel Lube), the control of the stepper switch was random. This means that the train movement was random, and so the time to complete a circuit of the layout was essentially infinite. It was a fun layout, and I am preparing to build even a larger one.
