This is exactly the reason I dislike reflowable formats. Younger people don’t seem to appreciate the benefits of the spatial position of information within a PDF/printed text. As an undergrad, by the time I finished a textbook chapter, I would have both the information and the general spatial layout of the text committed to memory. The latter greatly helped recall and cognitive integration. 30 years later, I can still pick up my undergrad textbook, dimly recall where the information is located, and quickly get back up to speed. The human brain has a powerful spatial ‘muscle memory’ for recalling information. This is lost when dealing with .mobi and .epub formats.