for this ubiquitous phrase
(at least in the case of books
) is due to a publishing secret
When a book is being printed, it is naturally not printed on individual sheets. This would be much too time consuming. Instead very large sheets, often equivalent to the area of 8, 16, 32, or more individual sheets are used. (But note the multiple of 4's)
This large sheet is printed and then folded and then the edges are cut making the individual sheets. The folding of this large page also varies. The large sheet will contain continuous numbers, say from 17 to 32, but they won't be numerically ordered, left to right, top to bottom. Rather they will lay such that when folded and cut, then they are ordered.
All this must be worked out by the person doing layout if there are a limited number of pages with color. Then, for example, only one large sheet will be in color; the others black and white. That's why a book with just a couple of colored pages will have them all relatively near one another, possibly all at the center of the book. To put them on two separate large sheets would cost more.
Also, this means that a book will always have as many pages as a multiple of the large sheets. If the large sheet contains 16 pages each, then the book will have to be some multiple of 16. Then, there are almost always pages left blank. Hence, the message: "This page intentionally left blank" so that people don't feel gypped.
It's always a trade off : either too many pages (wasteful) or smaller large sheets (more expensive). C'est la vie.