And the page numbering shown is calculated when the book is opened. The algorithm used is described in
https://wiki.mobileread.com/wiki/ADE#Page_numbers.
But, what it means is the number of screens used for each "page" changes depending on the formatting of a page and the font sized used. But, it is consistent across all Adobe RMSDK based ereaders for the same epub.
If you want one page per screen, you can convert the books to kepub. This uses a different ereader application and handles page counts differently. Each screen is a page no matter what the font size is.