From a person who writes 6000 words in a day and a half to not a single word in a fortnight, I personally feel, daily writing, weekly targets and similar depend on your individual style.
Doubtless, it is a noble goal. But doesnt ever work for me. I write almost every week, and when I do, I write in gushes. And then there can be some weeks of soaking in stuff (from seminars, readings, project work and similar) and suddenly a spark of an idea or an entire argument revised and again a gush of fresh writing...