Hi Athena. I think you will find most crime writers are on a shorter deadline than literary writers. The demand for "product" is relentless so if you want to maintain high quality it is important to treat the writing as a job which it is. For a professional writer that's exactly what it is. And like all jobs, you don't enjoy every minute of every day or even necessarily sit down to write with a feeling of anticipation. It is hard, mentally-draining work and, with a year to write a new novel, I would fail utterly unless I set daily targets. I am particularly lazy and only aim for 1000 words a day, knowing that sometimes I'll be over and sometimes under. I try to keep office hours (which means no weekends until the heat is really on) but writing is such a sedentary occupation that I'll often go for a walk or a swim in the afternoon. However, to do so, I must reach my target, as once I break off that tends to be it for the day.
It's the classic dilemma for the self-employed. Although you are master of your own time, you have to supply the self-discipline to keep up with the work.