> Imagine opening a book and 20% of the page are decor, decor with text no less.
Regularly happens in "book world". Chapter headings are often an entire page, and sometimes even a double spread. The average whitespace around headings on the three closest books at hand were all 1/3rd of the page, making that decor even greater than the 20% you're describing.
House of Leaves is a book like this and the story is not the same without it. The words move down the page in a staircase fashion as Will Navidson is walking down the stairs to his untimely demise, in one example.
Regularly happens in "book world". Chapter headings are often an entire page, and sometimes even a double spread. The average whitespace around headings on the three closest books at hand were all 1/3rd of the page, making that decor even greater than the 20% you're describing.