Not sure how correct, but I read somewhere some time ago that a developer is productive for around only two hours per work day. I rarely worked as contractor,

Not sure how correct, but I read somewhere some time ago that a developer is productive for around only two hours per work day. I rarely worked as contractor, but at most of the places I worked at, if I did my work on or before the deadline, nobody cared what I did. If I finished work early and volunteered for more, then I got better reviews and raises. Unless you are working retail, the hours shouldn't matter much.