A blog called Study Hacks by MIT grad Cal Newport posts information to help college students be successful, but a not-so-recent post from 2007 called "How to Schedule Your Writing Like a Professional Writer" provides some insight for aspiring writers and those seeking to increase their word count. Newport researched the available interview reports from several well known nonfiction writers (he was doing this for students writing theses and dissertations, so nonfiction was a closer parallel than novels) and reported out what he found about their writing habits. His stats on where, when and how writers writer are based on a limited set (eight men and two women) but are still of interest. The writers almost all favored morning hours for working (not as helpful for those with a day job) and writing in a specific place with as few distractions as possible. Phones, email and internet access were included as distractions; I can agree with that, as I write on a laptop with no wireless card just so I don't stop writing to check email. I do wish he had found info on more women writers.
A lot of Newport's other posts look interesting, too, if you want to think of writing as an extension of "study habits."