I try, as much as possible, to put symmetry in my PCBs. I try to keep trace spacing the same and even put parts consistently oriented. It's not always possible, but I always seem to at least try to do it that way. It is kind of an obsession.
I tend to go from a rats nest to refined. As I confirm that I have indeed gotten things wired out correctly and that I am not likely to make any changes to that section, I then start nailing things down a bit better. This is somewhat the way that I do my PCB work as well. Everything is a bit of a mess, but then I play and refine till I get what I am looking for. I hate leaving things as a rats nest. Even messy computer wires on the back of a computer bother me. I usually end up bundling them up into nice wire bundles.