Book page counts are multiples of 16 (or 8)

Books are printed in large sheets, with 16 pages (8 sheets x front/back) grouped together before binding. Therefore, the page count will always be a multiple of 16 or 8. This means content sometimes has to be cut or added to fit the page count. Apparently, some people have desperately compressed several pages of content, while others have written 10 pages of afterword (lol)