[Teresa Edgerton]

Some writers don't care a great deal about continuity, figuring each book stands or fails on its own, and that's that. The late Marion Zimmer Bradley used to incorporate massive rewrites of Darkover history into the plots of later books. She'd even do this with the personal histories of her characters. Then she would go back and write a completely different version of their backstory and get that published. Very confusing, but her fans didn't seem to mind.

Other writers try to be utterly meticulous about continuity from one book to the next. (Although I will say, even with the best intentions, doing this does get harder as the mind ages.)