Writing is an intensely cerebral activity, so much so that sometimes an author—perhaps even you—becomes so lost in abstract thought that they lose track of the idea that what they’re trying to produce is a physical object that can be held in the hand, namely a book.
And it’s the physicality of the book that sometimes creates a problem. One of the first elements to be decided in designing a book is how large the page is going to be. For some types of books, the answer is either a given or is limited to a small number of conventional choices if the publisher is going to have any chance of staying within a production budget. As an author, if your book contains tables or illustrations, you need to be aware of that page size. This is true throughout the design conversation, right up until the final stage of page layout.
Why does it matter? you ask. It matters because the complex diagram you’ve constructed may be suitable for a wall poster but may not be readable if it’s reduced to the space available on your book page. And if it has to be readable on your book page, yer gonna need a bigger boat, er, book.
Because paper doesn’t stretch, much as we might wish that it did.