I go through stages when it is nearly impossible for me to concentrate on anything other than the current writing project, and that's not very helpful when you owe 40 hours of your time elsewhere. As I'm driving to work, I get images and ideas, and "listen in" on my characters having an argument. By the time I get to work - I'm very ready to write, and sketch, and take notes. I can't quite do that, seeing that I have a job to do.
My brain is being torn in two opposite directions!