I would love to see some examples of vertically integrated industries on your layout.
Whether you have a toy train theme or a detailed, scale, prototypical layout, having a connected industry or industries gives the layout purpose and a “job” to do.
Forest/lumberjacks -> Log Loader -> sawmill -> Lumberyard -> construction site(s)
Coal Mine -> Coal tipple -> powerplant or RR coaling tower
Oil field -> oil storage facility -> refinery -> diesel fueling station/vehicle gas stations
Which industries are on your layout? Which levels of the industry do you model? Where are the different stages of the industry located in relation to each other on your layout? How do you like to operate your trains to service these industries?