Is selling individual chapters a valid marketing scheme? Is there anything against it or examples where it worked to sell a whole novel?
Most answers say "it's not a good idea" and that's what I'm going to say as well, but offer an example.
Besides commercial or professional work, I occasionally visit fan-fiction platforms as well. And there, serialising a full work like you are asking about doing is pretty standard - a precious few only start sharing after they are done with at least the first draft, but most write it as they go. It makes sense that this is popular, after all, it's a profitless work, you mostly do it when you have a free time and not concerned about saving that time for making money, so people just get their ideas out and get excited to share them.
Now, the reason I am talking about this seemingly unrelated topic is - even on a platform where people visit mostly for fun reading, and is legally completely free of charge, a lot of people avoid serialised work like this until they are complete. Reasons are simple: one, if the author is publishing chapters as they write, it may come a time where they can't write anymore, whether it be for personal reasons or a common writer's block, and the chapters will either come less frequently or stop coming entirely. This particular reason can be irrelevant to you if you have your work ethics and professionalism to be consistent with publishing. However, second reason is much more psychological and why I'm not fond of the idea: most people don't want their reading pace to be controlled by the lack of content.
Even if a person finishes a novel in a year, it's comforting to know that if they want to read more of that novel, it's right there, without having to wait. Memory factor is also persistent - if you are made to wait for a new chapter outside of your will, you may get emotionally disconnected from the story, forget some plot points, or both. Readers like to control their own pace when it comes to novels, they don't expect it to be like a TV series to wait for weekly.
But why wouldn't serialising work for novels if it works for comics and TV shows? I personally can think of many small reasons that wouldn't work alone but are strong combined, however, I suppose one big reason would be the company discipline. You are talking about self-publishing your novel, and for serial work, that's way less reliable for a customer than an established comic company like Marvel or Shounen Jump where the customers know they'll get what they want, except for the few occasions that has been announced and they know won't be an habit due to the company discipline. An individual has so much more to prove while they are in the process of getting known, and that's one aspect of why serialising a self-published novel is a bad idea.
There is also a culture aspect to this. Unlike comics or TV series, people don't expect to be able to access to a novel chapter by chapter - novel series sure are a thing but even then you can get your hands on a full novel instead of a single chapter. This is of course not impossible to break into normalising the idea of a serialised novel, but this idea needs to prove its reliability first. Basically you'd have to live a whole lifetime with little to no profit if you want to popularise this idea on your own. Even then, it's not guaranteed to success, since it's tough to break traditions alone.
And if you're going to get most significant amount of readers when you're done with the novel, you might as well go for publishing the novel when it's done as a whole.
TL;DR Demand for an incomplete work tends to be infinitesimal and a paid chapter is not the best way to advertise it. You could publish a free portion with the promise to get to the full thing with money, but a periodic publication is not very ideal in this age of impatience and lack of appropriate literature magazines.
Serializing a novel has been done before - traditionally this was done as part of periodic publications (so you would get say a chapter per issue of a magazine) but it has been done outside this environment as well.
The only recent notable example that comes to mind is Stephen King's The Green Mile which was released in six smaller volumes - this worked IMO but there were some key differences from what you are proposing:
Firstly the released sections were probably more substantial than a typical "chapter" - each was between 92 and 144 pages long. Secondly King was already an established author - and having his name on the cover was always going to bring people along with his "experiment", he wasn't trying to use this as a way to market the book - it was a creative experiment where he (and his publishers) relied on this star power to overcome any skepticism.
Does that mean you shouldn't do it?
Not necessarily - but I think you are going to be putting quite a substantial amount of work and pressure on yourself. You would need to be able to stick to a release schedule, keep the "chapters" written in such a way as to hook people back for the next one and price them attractively.
Ultimately unless you are really planning on using this as a creative tool to format your story in a episodic manner then all you are doing is offering the reader a less convenient way to read the book, and I think that's going put more readers off then it entices.
So if you're plan is just to take a "normal" novel and release it piecemeal then I think you should reconsider.
I haven't heard of it. When you can get whole books for free, and many books for 99c, this seems an unlikely route to successful marketing.
If any piecemeal approach has a chance of working, I'd suggest giving away 3 chapters for free, as a free sample of the writing quality, with a payment for the rest of the book.
There are some authors using a scheme that seems pretty successful, in that they have one set of books they give away for free (cycling through, like changing the free book every three months), and they sell the rest of the books (including some that are never free).
For example, if you wrote a series, give away the first book, but sell all the other books in the series. Hopefully, enjoying the first book motivates them to buy the rest of the series.
Here's the MAJOR SUPER IMPORTANT trick of giving away books or anything else for free: To get the free item, readers absolutely positively must register on a site with their email address. You will either email them the book, or email them a link or secret one-use code or something that lets them get the book from your website.
They may end up sharing your free book, that's fine, it is an advertisement after all! Just make sure you have a page up front (with your copyright info or dedication page perhaps) that lets other readers know, in large letters, where your website is so they can visit it themselves, and register for some other free book. Or register to buy the rest of the series! Heck, you could put your website address as header (or footer) on every page, in an 8-point font.
Give people rewards (like another one of the free books, or half-off your next book, or something else that doesn't cost you anything) for referrals that get registered.
Always be building your mailing list, whenever you finish another book, these are the people you want to sell it to.
In the comics world, this is normal.
Each issue (the standard is 22 pages, not including the cover and publisher additions) comes out separately, either as an e-comic or on paper, or both. After at least 4 issues, but generally a year's worth, which can be 4-12 issues, the comic is collected into a book. Usually these are volumes of a larger work, but it can also be a standalone book.
Outside of the comics world, this used to be done for novels as well, but just isn't anymore. At least not often.
Chapters in novels would be serialized in magazines. There just aren't a lot of magazines that publish short fiction anymore. Sure, there are some, but they mostly want shorter pieces.
If you are self-publishing, then ask about your audience. If you're hosting your own platform, like a blog, then you can dole out your story however you wish. But you tagged this question amazon which implies you mean to sell your book there.
Marketing a teaser chapter, or a free one, could work well for you. But serializing a novel on Amazon? Unless there is a market for that I'm not aware of, it doesn't seem to make sense.
Think also of the timing. Either you would be delaying the release of your novel for many months in order to play up marketing, or you would be releasing chapters as you write them. Neither is a good idea.
You don't generally get more than one chance to sell a book online. Someone is browsing, they find it and decide to buy it. But wait, it's only one chapter and only 4 chapters are available now. They're likely to walk away.
If you release chapters as you write them, you give up the ability to edit them. Sometimes you don't know you need to make edits until you've written new chapters and need to go back and make things consistent, or add some foreshadowing, or even introduce a new character. You may change the order of scenes or make other large changes. Then, when the entire book is done, you're probably going to do some restructuring.
Another consideration is money. If your chapters come out in a monthly magazine, that's one thing. But on Amazon, are readers really going to pay a dollar per chapter? That's the minimum list price per item (99 cents US, or the equivalent in other currency), unless it's free.
You're much better off with a teaser chapter published on your blog and/or in a magazine or anthology if you can, along with a free chapter in your Amazon listing. But publishing the full (and fully edited) novel as a whole.