Quote: "You still have to set up some coordinates, the mesh needs to know how to lay the texture down, so the question still stands,
Do you unwrap the mesh or just apply some simple face mapping?"
Okay, if your segment is more than a box, then you will have to set UVW maps for each area of the mesh that is different...just like any other model. If the segment is a box object, like a 100x100x5 wall segment, then apply a box UVW map and set the dimensions to 100x100x100 (if you want the map evenly spaced all around the segment.
If the segment is a wall with a doorway pre-cut into it, then set it up with a UVW map, box, 100x100x100 like before, then select the parts of the frame that you want scaled differently and apply new UVW coordinates to those areas.
You question's not a simple one. Do you have to unwrap? Yes, No, we don't know. It depends on your mesh object.