I will confess that sometimes cleaning my physical environment can have the effect of clearing my head, but it's probably due more to the act of doing it rather than having the clear space.
I lived with a roommate that taught me how to keep the common areas in the house clear, and to have a place for everything, and I mostly do that. When I get ready in the bathroom in the mornings, I don't leave my stuff out for others to have to deal with--it goes back into whatever place I got it from. What I do tend to do, however, is nest--if I'm going to be sitting in the same place in the living room or my bedroom every day and need the same stuff, I'll just sort of keep a little nest of that stuff around me. If I'm going to need it, I figure, keep it convenient. When I'm done with it for good, I'll put it up.
I would say I'm somewhat messy, but I'm not gross. I'm not going to leave nasty dishes piled up for weeks, or never clean the bathroom. I have been to people's houses that seem like they should be condemned for health reasons. I couldn't live like that. But stuff like making the bed? Yeah, I might do it once in a great while. It just seems like a waste of energy.