Yes, I enjoy a good mountain route. I merged the Clinchfield into Deremmy's East Kentucky way back in TS2010. That was quite an operation that took me hours to operate. My current mountainous route is my Legend of the BNSF 1 merged with II and then merged with the Eagle River and some others. This extensive operation covers the Pacific Northwest and some of the Idaho-like operations of the Great Northern and BNSF. I get to run long containers, lumber and tourist operations, and long-distance passenger trains. This too takes hours to operate and I have simple AI instructions, mostly to go back and forth so I do the complex stuff in between.
As far as your interior thing goes, I'm curious about that, but if it's not causing a problem. I wouldn't worry about it either, but like you said it does bug you as it would me as well.