What makes Busiek's continuity-wrangling work and someone like Roy Thomas's (bad day Thomas, not good day) not is that it's always done in the course of an actual story. Back around the time his run began, a bunch of Avengers fans gathered a list of continuity knots and dangling subplots that the series had accumulated and sent it to him. He responded by saying that, if he found a way to address any of them in the course of a story he was already going to tell, he would, but he wasn't going to go out of his way to do so.