It depends. If it’s been a long time, I’ll reread (Or at least look up specific chapters). It depends on how much the story is “present” in my mind as well. The Stormlight Archive and The Reckoners were solidly in my mind for a few years and I have enough a grasp on the story that I’m in control of it and can work with it the way I need. When I get back to The Rithmatist, however, I’ll need to reread the whole thing.