Just remember if you use two different versions of a material (horizontal and vertical), you increase the file size and potentially reduce performance and speed. If you have to edit the materials, you have to edit them both. You waste even more time that way. Applying and aligning a material isn't at all difficult to do in the model and once you've set it to each required orientation, you just sample the needed orientation when applying the material to other faces. Still, as with most other things in SketchUp, you can choose how you want to invest your time and how much to invest.