I get roughly 50% more book space per shelf by using the Lagerfeld Stack™. Browsability is a nice benefit, too. You may want to consider converting to the Lagerfeld Stack™, depending on the dimensions of your shelves. https://twitter.com/wheatpond/status/951570494347710469 …
NB: The punctuation of books stacked in a conventional, vertical fashion are an aesthetic extravagance reserved for those with an outrageous penchant for the luxury of spacial inefficiencies.