As a reader, I like the whole article on one page. For that reason, I've never split up an article, even a couple of very long ones of about 6000 words. I like to use subheadingss and images to separate sections of text.

It depends on the article(s). As noted above some like to keep it all in one. Others will split... figuring that is just that many more places to put ads. I don't buy into that as the user, if they click the ad, will usually not see the rest of the article. As for SEO... the doc is the doc, the indexing is the indexing.

I have a few sites were the SMALLEST document is just under 100,000 words (sic, no mistake) and goes up from there. I don't split them unless there is a good and logical reason to do so, ie, bibliography, appendices, related but not germane, etc.

So far I have not seen a difference between those sites and others which are in the 300-1000 word pages for SEO purposes.

In short, design for the user not for Google.