As John Grisham keeps up his phenomenal workrate, what is the secret to avoiding writer's block?
Suddenly, there's a new date on the calendar. Close observers report that it's been there since 1991, but only in the past couple of years has it begun to be noticed. Timed to fall just before St Valentine's Day, it makes a lot of people excited, a few rather unhappy, and one man very rich indeed.

Grisham Day, which falls this year on 4 February, is the date fixed for the American lawyer-turned-novelist John Grisham to bring out his new book. He began his first, A Time to Kill, in 1984, and because he was still in legal practice then, and had to write in early-morning stints before going to work, that novel took him three whole years to complete. After its phenomenal success, however, he was able to devote himself to writing full time - and since 1991 he's published at the rate of a book a year.

The Testament, his 10th novel, betrays no signs of authorial flagging. Since it runs to 435 pages, I'm not giving much away if I disclose that it begins with a self-made, wheelchair-bound billionaire, the 10th richest man in America, pulling a testamentary fast one on his loathsome children by leaving all his wealth to an illegitimate daughter who lives with a tribe of Indians in the deepest jungles of Brazil. Having signed the will, the billionaire then throws himself off the top of a tower block, and his lawyers have to pick through the mess. The death-leap takes place on page 17. Now read on...

And people do read on, and on and on, in extraordinary numbers. In the US alone, 20 million copies of Grisham's books have sold in hard covers and more than 70 million in paperback. The Pelican Brief stayed in the hardback bestseller lists for 48 weeks, and The Firm and The Client 46. At one point, Grisham topped the hardback lists with The Chamber and had paperbacks at numbers one, two and three. He has been translated into 28 languages, and at least six of his novels have been adapted as films.

But not everyone is delighted by Grisham. Lawyers deficient in a sense of humour don't care for his portrayal of the profession as one ruled by greed. Literary historians mutter that it's unfair for Grisham to be credited with reviving the legal thriller: Scott Turow has a prior claim, even if his books don't sell in such numbers. And though several lawyer- novelists have become bestsellers as a result of this revival - Philip M Margolin, Richard North Patterson, Dominick Dunne, Philip Friedman, Steve Martini and Nancy Taylor Rosenberg - other wannabes resent having missed out. There are Grisham's sales figures to envy, too: in 1996 his royalties ran to $30m, and with movie spin-offs he has now earned more than a billion.

THOUGH THERE'S more than enough here for any averagely envious British writer to resent, this isn't the reason that some of us feel gloomy at the prospect of Grisham Day - and why we're planning to cheer ourselves up by going to Tom Stoppard's film Shakespeare in Love, which shows the Bard suffering from writer's block. Because it's not Grisham's sales, or looks, or money that hurt, it really isn't. What's sick-making is his speed and efficiency. The bastard publishes a book a year.

"Churns out", I was tempted to say, but that would have been snooty, and Grisham rightly makes the point that "Updike comes out every year and nobody accuses him of just cranking them out". Updike isn't the only novelist to combine a fast work rate with a serious critical reputation. A new Anita Brookner appears each summer. Fay Weldon, Beryl Bainbridge, Ruth Rendell and/or Barbara Vine are there most years. Still, they're not such clockwork performers as Grisham. Even when he ditched a novel a third of the way through two years ago, he still met his annual 31 December deadline.

To accountants and marketing departments, an annual cycle like Grisham's makes sense - at least until familiarity breeds contempt. For most authors, who have to live off royalties and advances, it makes economic sense but none aesthetically: a book takes time - two years, three, even 10. Of course, we'd all like to write with effortless speed and brilliance. But if writing doesn't run swiftly and smoothly, that's probably no bad thing. Speedwriting encourages speedreading and, as Dr Johnson said, "what is written without effort is in general read without pleasure". Thrillers may be a special case, to be set and solved as briskly as crossword puzzles. But with most writing - whether fiction or poetry, biography or philosophy - it takes time to get things right. Researches have to be done, and ideas nurtured, for which a year feels far too short. The writing stops. Or never starts. Or if it's going well gets sabotaged by life. You can be organised, put yourself at a desk, draw up schedules and all the rest, and still produce nothing worth keeping. A word sometimes used to describe what's needed is "inspiration".

Dr Johnson was impatient with the idea of inspiration, and said a man could write at any time if he put his mind to it. Anthony Burgess took this line, too, and, having been diagnosed (falsely) as suffering from a brain tumour, set out to write as much as possible in a year, in order to provide for his widow: "Two thousand words a day means a yearly total of 730,000. Step up the rate and, without undue effort, you can reach a million. This ought to mean 10 novels of 100,000 words each." Though in the event Burgess produced a mere "five and a half" novels in a year (including A Clockwork Orange and Inside Mr Enderby), this was, he boasted, "nearly EM Forster's whole long life's output". Still, many of us would rather have Forster than Burgess. Or Larkin (four slim volumes in 40-odd years of writing poetry) rather than Pam Ayres. James Joyce (1882-1941: three novels and a collection of stories) once took all day to get the right word-order in a single sentence. Part of the point of good writing is to slow you on the page - you can't (as with Grisham) merely skim down the middle for plot. Great books have been written at great speed. But not often.

Writers sometimes speak of their books as children, and don't expect to produce too many. Those with more active birth rates are suspected of resorting to "formulas", artificial aids and outside help. John Grisham owes a debt to his first agent, the late Jay Garon (who, out of four one- page synopses presented him by his client, chose The Firm), and to his second, David Gernert, who (he freely admits) steers and heavily edits him. The formula that helped him was an article in Writer's Digest giving 10 tips for the production of suspense fiction. "Know your destination before you set out" was one of its injunctions.

WITH SUSPENSE fiction, this rule probably makes sense. But if they knew where they were going when they set out, most mainstream novelists wouldn't feel it worth the journey. Discovery is part of the point. And if the destination is uncertain, so will the delivery date be. Deadlines can be a spur, but also a distraction. Many a novel has come to fruition after passing its due date. That's the worry about Grisham Day. It's not hard to imagine a conglomerate publishing future where novels will be untimely ripped from their makers in order to meet promotional schedules.

It would be easier to say all this if Grisham the man were an unpleasant customer. But sadly for the mealy-mouthed, he seems nice beyond belief: young, handsome, happily married with two children, self-effacing, well-connected (Bill Clinton, one of whose grandfathers was a Grisham, is his 16th cousin), a Little League baseball coach, a Sunday school teacher, publisher of a literary magazine called The Oxford American, a supporter of writing programmes in several universities and a man involved in charitable works. "A Baptist, he periodically travels to Brazil with church groups to build chapels for local congregations," ran a recent profile. It doesn't sound much like Hemingway or Scott Fitzgerald. Perhaps that's why Grisham's books are so popular: they're eco-pious, wholesomely all-American and don't have any sex in them.

Grisham has said that he's worried about the impact of him "skipping a year" on small bookstores. Very philanthropic. But for the sake of other writers, and for his own prose style and sanity, I'd like to see him slow down. Come the next millennium, he should resolve to fall into slack habits - to malinger, procrastinate, have that extra cup of coffee and, when he does get to the keyboard, to sit and brood a bit over the words. Grisham fans will love The Testament. I didn't mind the couple of hours I spent reading it myself. But given the implications of the Grisham phenomenon, I couldn't help thinking of a line of Dorothy Parker's: "This is not a novel to be tossed lightly aside. It should be thrown with great force."

`The Testament' by John Grisham is published on 4 February by Century at pounds 16.99.