What is a songwriters work day like?

Some songwriters like Oscar winner Dianne Warren have a very disciplined schedule. Rear end in the chair by 9am and the work day doesn't end until the whistle blows at 5 or 6pm, with a break for lunch. Others, live a more Bukowskian lifestyle of all-nights and dry spells that last for weeks. Some songwriters catch a plane to spend two weeks working in-studio with an established recording artist, living in a motel room for the duration.