Great benefits from the single texture mapping style, get this...
First you map your ass off neglecting the texture crap.
Then you look at your environment and pick out or make textures that fit your archetecture and light things perfectly. Consider it like a preview of what your working with when making textures. Then you spend the rest of your time texturing crap like you normally would, only it's like painting on a blank canvas. Add your details like {mask_textures and !water since these are hard to apply without the actual textures. once you're done, replace your starting texture with null textures. This should cover all of the places on the func_walls and such you may have missed. Compile and play
I also discovered that in the professional world, two different people do the textures, and the map. I guess this is the method they would go about doing so. It makes much sense to me. I always mapped applying textures and details as i went along. Usually a process of overloading detail, then cutting detail to fit within the limits of the engine. I never really liked this part cuz it threw things off. With the single texture method, it's easier to add and subtract brushes.
i hope this helps someone, cuz i'm sick of listening to myself...