Yes, it’s another treatise on programmer productivity, but it’s still ever so true. Of course, this applies to any occupation (engineering, writing, design) requiring long bouts of concentration to be productive.
…[W]hen you are in the flow, you concentrate only on what you are doing and you hold all the required details in your head, in the short and middle term memory. Because there are no disturbances inside your own head, all the details are readily accessible to the brain and the brain in general works like a well-oiled machine, the work progresses excellently and working is a pleasure.
This piece actually had its beginnings as a message to the writer’s employer’s internal mailing list.