We live in a hyperactively hurried, time-poor world. Music, films, television and the internet all compete for our attention, leaving the slower pleasures of the good old book seeming hopelessly old-fashioned. Who, after all, is going to have the time or the inclination to switch off into the fictional world of the printed page for hours at a time, when there's so much stuff going on?
And yet the past month in the publishing world has suggested that, far from pandering to the vagaries of 21st-century fashion by offering an exclusive diet of short stories and novels as iPhone apps, the balance is tipping towards the door-stopping epic.
The Japanese author Haruki Murakami's new book, 1Q84, is a back-breaking three volumes long. Stephen King's 11/22/63 takes 849 pages to explore what happens when a time-traveller tries to prevent John F Kennedy's assassination. Then there's George RR Martin's latest instalment in his best-selling A Song of Ice and Fire fantasy series. A Dance With Dragons is 1,040 pages long - and that was after a judicious edit trimmed out nearly 600 pages.
Murakami's literary opus is an interesting case, as lengthy books have traditionally been the preserve of fantasy authors such as Martin or Tolkien. There are always exceptions: Hilary Mantel won the Man Booker Prize in 2009 for the 672-page Wolf Hall, the tale of Tudor England (a mere slip of a thing by Martin's standards, but still double the length of a "normal" novel) - but even she told The Guardian last week that the follow-up would be "shorter, more concentrated", in feel.
The Booker judges aren't wholly averse to enjoying a proper epic - the year after Mantel's win, Paul Murray was longlisted for Skippy Dies, also 672 pages long. The book came as one chunky paperback or three beautifully bound volumes - both options were quite an undertaking. And unbelievably, it all started as a short story.
"And a couple of years later, it was well over a thousand pages long!" laughs Murray now. "The story was supposed to be a two-hander about a history teacher and one of his students, but as soon as the teacher stepped outside his classroom at the end of the first scene I found the whole world of the school there waiting for me. I enjoyed writing about that environment so much, and it kept generating new ideas, which was really exhilarating."
Of course, the obvious danger for any author who decides to tell his story this way is that the novel loses both its focus and the attention of its readers. In a school, where there are plenty of characters to explore, multiple threads and digressions can be the source of endless entertainment. Still, even non sequiturs need to be there for a reason.
"On the technical side, keeping track of so many storylines can get really difficult," Murray admits. "Your walls slowly fill up with charts and plot outlines and your room starts to look like it belongs to a serial killer. But the other big challenge is financial. You're in a race against time, trying to finish the book before the money runs out. It can get pretty tense."
Incredibly, for Murray, this was a seven-year process, and he counts himself fortunate that he didn't have any other commitments besides "feeding myself". His publishing company was happy to wait. But would it always be so keen on humouring the whims of its authors? The Penguin and Hamish Hamilton publishing director, Simon Prosser, isn't sure.
"Depends who it is," he smiles. "Vikram Seth is currently working on a follow-up to his epic-length A Suitable Boy, called A Suitable Girl, so obviously I would be entirely happy if he called to say it was 900 pages long.
"If Lydia Davis, best known for her micro-stories, told me she was planning an epic, I would probably be very surprised, but of course excited: it would be something new for her, and fascinating to read."
Seth's A Suitable Boy is a notable example - at 1,349 pages, this Indian family saga is not just long, it's one of the lengthiest novels in the English language, full stop. More than a million sales later, it's fair to say the commitment it asked of its readers didn't put them off.
"I have seen multi-part television dramas described - positively - as 'slow TV' - and perhaps something similar might be said about these novels," says Prosser. "They're books that allow readers to inhabit a fictional world in-depth and for a significant duration of time, the length of reading echoing and perhaps reinforcing the sense of lived life and history in the book itself.
"The very hard thing, of course, is sustaining a novel successfully over an epic length. It isn't easy. It requires a great grasp of pace and structure, and the ability to marshal, typically, a large cast of characters, all of whom may have fairly detailed back stories.
"The challenge of writing fiction is always in some ways architectural, and, as in building design, the grander the project, the more complex the planning."
So is there a trend for longer books? Prosser's not so sure. For every "maximalist", he says, there's a minimalist. Julian Barnes won the Man Booker Prize for The Sense of An Ending this year, and it was a paltry 150 pages long - one of the shortest ever. Prosser has also worked on Mohsin Hamid's The Reluctant Fundamentalist - only 74 pages longer than Barnes's book - and thinks shorter novels definitely do something different.
"They plunge the reader directly into a conversation," he says. "Hamid's technique is brilliant, but it has an intensity that might be difficult to sustain over 1,000 pages."
Of course, buying the book is one thing. Actually reading it, rather than showing it off on bookshelves, is quite another. But Murray thinks people not only enjoy the languorous pleasures of the epic but still have the attention spans to do so.
"Time poverty is more of a perception than a reality. For me, I love a long book. I like getting to know the characters over a prolonged period. I've been reading Marcel Proust's In Search of Lost Time for the past six months. It becomes a kind of parallel world - which maybe has a stabilising effect on the actual world you move around in. Comparing that with a short book is like a trip around the world versus a two-day city break. One changes you forever. The other you spend most of your time trying to get out of the airport."