When I read Dombey and Son (1846-48), I noted that it seemed to demonstrate a much higher level of planning than the prior Dickens novel I had read, Martin Chuzzlewit (1843-44). The structure of Chuzzlewit very much demonstrates (to me anyway) that Dickens must have been making it up as he went along, with its diversion to America and the fact that Martin (a damp squib if there ever was one) pretty much stops being the protagonist of the novel that bears his name.
Dombey and Son, on the other hand, is very obviously planned. It ran nineteen monthly installments, the last of which was double-length, making for twenty in total. At the end of every fifth installment, something of great significance happens: the death of a main character, the marriage of a main character, the flight of a main character. It's like watching the season finale of a modern serialized streaming show. I was curious about this, and reading the introduction to my Penguin Classics edition suggested that Alan Horsman's 1974 Clarendon edition of the novel would provide a detailed account of novel's composition, so I ordered it through interlibrary loan.In his introduction, Horsman cites Dickens's friend and biographer John Forster, who had "stressed the contrast between Martin Chuzzlewit and subsequent books like this one which showed Dickens 'more bent upon constructive care at the outset'" (xv). Horsman argues that Forster is exaggerating a bit, as we know that Dickens had Chuzzlewit's ending in mind from the beginning. But I think (to put it awkwardly) that Horsman is exaggerating Forster's exaggeration. Sure, Dickens had his plot twist in mind the beginning... but clearly he did not have the beats and pacing in mind from the beginning in the way he did in Dombey and Son. Had he precisely planned everything in Dombey? I don't think so, based on the evidence Horsman cites, but we do often see evidence of him working ahead a bit. For example: "On 6 December [1846] he was occupied with the first chapter of Number IV. 'Paul, I shall slaughter at the end of number five'" (xxvi). And later: "As one would expect, the planning of Number V is very careful" (xxviii).
That said, things do get a bit looser later on. Dickens had a broad-strokes idea, but didn't have the precise planning worked out from the beginning: "The problem which the memoranda for Number VI emphasize is to continue throughout the remainder of the novel…. February letters show that he found it 'very difficult to fall into the new vein of the story'" (xxix). Perhaps this why I found my interest in the novel diminished as it went! It seems like Dickens had a lot he knew he wanted to get done by the end of no. v, but having crammed this all in, was less certain about where he was working toward for the remaining fifteen installments: "The second marriage [of Dombey] has now to sustain the greater part of the novel… he was to warn himself 'To bring on the marriage gradually'" (xxxi-xxxii). Horsman chronicles how Dickens thought of other aspects of the novel to pull into the foreground, but also how Dickens wasn't unlimited in what he could do; there were things he planned on that just didn't pan out.
Horsman doesn't mention those big turning points I identified in nos. x and xv in the same way, so it seems likely these weren't planned quite so rigorously in advance as the ending of no. v was. But it is clear that Dickens was being deliberate in his pacing in a way he had not been in Chuzzlewit, even if this ultimately undermined (I would argue) the success of the novel as a whole.
Forster said that, "for Dickens, 'the interest and passion of [the story], when to himself both became centred in Florence and in Edith Dombey, took stronger hold of him, and more powerfully affected him, that had been the case in any of his previous writings, I think…'" (xxxii). Again, Horsman seems a bit skeptical of Forster's claim, calling him "defensive" (xxxii), but I agree—going in publication order, for me this is Dickens's first novel to have some genuinely emotional moments, even if he would get better at this later on. And Forster also says the second half "seemed to many to have fallen short of the splendour of its opening" (xxxii)—and again, I agree. Because Dickens had to get to that twentieth installment, much like how a modern streaming show has to get its season out to ten episodes no matter what, the later parts of the novel are less dense with incident than what came before.
It's also fascinating to learn how down-to-the-wire Dickens's composition could be; there were times Dickens had to send in each chapter of an installment as he finished it to have enough time to be typset. There were even times that a chapter had to be broken up by pages so different typesetters could do different pages simultaneously! In such a down-to-the-minute environment, I suppose the more planning you can do in advance, the better.