Time, in writing a novel, has two aspects. Obviously there's the time the story takes place in, both the 'real' time of a scene with full(-ish) dialogue and action, and the gaps which the narrative either skims through ("winter passed eventually, and with the spring came...") or jumps altogether. But there's also the time it takes to read the thing. How often the middle of a book seems to drag; but is that the writing, or the events, or our attention? One reason I prefer to read the novels I do reports on in a long, single sitting, is that I get a much better sense of the actual proportions of the parts to the whole. If, perforce, I have to read it in two or more chunks because I can't find a long, whole day this side of Easter and the report's due next week, my sense of how long it is since the Y scene may be quite distorted. When I'm working on the report I'll find my note saying "Too long between X and Y - tension drops" and look at the MS, reading again across that gap, and find that it's not too long at all.
My process for Kindred & Affinity, is one I've settled on very comfortably over the last several novels. I write each of the ten chapters long-hand, not going back to tinker or revise, and then type it up, roughly sorting out the interlineations and balloons and asterisked chunks to insert, and checking up on little notes which say things like "has this been said already?" and trying to improve on the bit marked "right idea, boring words". Anything more major or likely to divert me for more than a few minutes is decanted into a new list of notes. The idea is to write as fast as possible, to get closer to the experience of a reader in the order and scale and connection of events, to allow whatever is unrolling to unroll, to write a shitty first draft.
Yet still, when I type it up, I find my sense of the wordcount of the novel is remarkably accurate, but my sense of how long - in readerly time - anything takes to read, always turns out to be completely wrong. It's not just that those 100 pages of longhand, which is a 13,000 word chapter* (yes, I have very big, sprawly writing and write on every other line to leave lots of space for changes of mind), feels like a lot of pages in a book, and yet hold many fewer words. It's also that, try as I will, the speed I write - which many of my fellows, especially the poets, consider quite fast - is ludicrously slow compared to even a slow reader. I type at about the same speed I write, or a little faster, so it's not that either. But it's made me realise that the experience of reading is intimately affected by how you read it: a few pages every bed-time; or in one mad summer day, hiding under the bed when your grandmother comes round to suggest that you could read Jane Eyre just as well out on the lawn "but don't forget a rug,"; or a third in, and then you lose the book, and find it five months later...
We talk of novels as absolute objects, and so much of writing-teaching is about getting new writers to understand that it's all in the re-writing: that if you're thinking "Oh, it'll do", then it won't; that you won't learn until you learn not to give up making something better; that somewhere inside you there's a 'best' version of the story, a 'perfect', a 'how it should be', and you must try to find it and allow it to emerge. And yet, not only is how it comes out contingent on when it was written - all my novels would be subtly or perhaps very different, I know, if they'd been written in a different year, or even a different few months - but how it's read is contingent on when it's read, and in what way. I'm sure this double experience of fiction time is something which gets played with by the writers of postmodern fiction, only I'm hungry, the supper's burning, and my brain's not working properly, so I can't think of an example. Even if you - as I do - sometimes find such fiction too tricksy to be more than amusing, it is interesting to contemplate the time and rhythm of the reader's experience: to look at the spacing and reach of the piers of the bridge; to set your stop-watch, and time the giant's strides.
*I was interested to hear Ian McEwan saying that he conceives of a novel from very early on in a similar way, 'knowing' the maths: that it's going to be three parts of 30,000 words each, or 'five times eight'.