There are pros and cons from a SEO perspective of breaking up an article into multiple pages.
A positive to breaking up your article into multiple pages is that it allows you to target different keywords per page and target your optimization for those keywords better. Chances are you will also have a higher pages per visit (PPV) data point for your site since most users will click through to secondary pages.
Negatives are that there is less content per page and a single page has to target all of the keywords for that article which can decrease the chances of the article ranking well for many different keywords.
A positive to a single page post is that typically people will link to the first page of an article so all of the link juice will end up going to the first page, but if the article is multiple pages and people are only linking to the first page then the secondary pages of the article will not receive as much link juice since it will be diluted as it filters down.
Personally, I have not had much success with secondary pages of an article ranking well, so I usually just focus on creating single page articles, but you could have more success.
I would not spend too much time worrying about it, but would rather spend your time focusing on creating quality content for your posts.