Stack of books

I know that when a book it placed certain surfaces, it turns into a small stack of book (2-3 books) and with one book standing on top. Perfect for retail bookstores.

But in the debug catalog there are some much taller book stacks (6-8 books?)! I have never seen those in game, and got curious to what activates them ? I suspect this is either retail (Get To Work) or related to the writer career (base game?), but I'm not sure.

Can someone please enlighten me on the stacked books feature(s)?