The code you posted does not split a Word document "into individual pdfs by each page". It processes a mailmerge creating a new file for each record. The number of pages for each record depends entirely on what's in the mailmerge main document, be that one page or one hundred.
The code for splitting a document is found under the
Split Merged Output to Separate Documents topic in the same
Mailmerge Tips & Tricks 'Sticky' thread you got your posted code from:
https://www.msofficeforums.com/mail-...ps-tricks.html. That code allows you to specify how many pages each new document should contain.