Lore devs; narrators, etc. What goes into making the lore?

Simple question really. I enjoy writing stories, and reading other people's works. What I've always been curious about is the established and now retconned lore that the narration team works on. How long would it take on average to write a piece, go back and reworking, peer review and then finally releasing that piece. I know a decent amount of players also hugely enjoy the lore, as it expands the world bit by bit. So it'd be interesting to hear it from the writer's perspective.