Is this really a normal amount of prep for 5e? With Paizo adventures I've only ever read the adventure in advance, collated some bits of information that are spread through the adventure so I can forshadow them, and made some brief notes on NPC accents. I can't imagine a group of players for whom prewritten dialogue would help me in the game, and I just use the book/pdf for actually running rooms and events. This is closer to the level of prep I do for adding in extra content or doing entirely homebrewed adventures.