This ties into track planning discussions, but I think I've seen this topic discussed here before (though I couldn't find the thread). What are the pros/cons of operating a layout focused on a single industry? For example, coal is going to be a major player on my layout. The other day, I stumbled across a website where layouts are dedicated solely to coal operations: Appalachian Railroad Modeling. On another note, would it be okay to have an industry focused layout? Meaning, to model more of the coal operations, yet still have other industry. Or would that seem unbalanced?