I always get a grin out of articles by the literati, who are appalled at the idea of an author writing a book every year. As if writing novels was the same as having illicit sex; and the more you do it, the more of a slut you are. As with all sorts of talent, those who don't have it are always stumbling over themselves to tell those who do how they should use it.
And as the song goes, it's in the way that you use it, not how little or how often.
There is some weight to this argument for the writer; if not for the reasons the literati would wash our brains with. Most of the published authors I know would be overjoyed to slow down. Wouldn't we all like to live the life of Lethem, and have a half a million free bucks to blow on good equipment, research, promotion, and all the other expensive stuff? Not that such a thing ever happens to writers who actually need the money.
Thing is, without a bankroll, or a very patient family or partner willing to support you, a writer hoping to keep writing full-time can't afford to slow down. And then there's the competition, which is getting outrageous. The working writer has to put out his or her best at least once, preferably twice, yearly simply to stay in everyone's little black book.
If you want to do that, you should start making some time commitments.
Work up a writing schedule based on what you want to accomplish over the next twelve months. Let's say, for example, you want to write two books a year, and that means producing 200K. If you write five days a week, and do your research, outlining, editing and rewriting on the weekend, that requires writing about 770 words per day, or three pages. At an average of an hour a page, that's three hours of writing time. Double that, write six pages, and you can produce four books a year -- if you can devote six hours per day to writing (for those who want to pace me, you need to produce three to five pages per hour, or thirty to forty pages per day, seven days a week, 365 days a year.)
This is not possible for everyone, and I wouldn't presume to say it is. For some writers, writing to a schedule is simply impossible because their lives are too erratic. Others can only write when mental/physical/spiritual conditions are perfect, and I understand those conditions can't be scheduled. You guys really have it tough, but I imagine all that chaos and spontaneity pays off in other ways for you all.
I'll be talking more about ways to increase your productivity this week, but in the meantime check out SF author William C. Dietz's article How to Write a Book A Year (.pdf file format) here. He has some good pointers on how to handle the work of writing one book per year while holding down a job, hanging with your family, having a life, not going insane, etc.