In any case, the time travel aspect of Azkaban always bothered me. I think making time travel a possibility in Harry's world was the single worst mistake that Rowling made in the series, because that leads to the question -- why didn't Aurors USE them to stop Voldemort before he gained power? Or, if they were a recent invention and they couldn't go back too far, why not go back and stop Voldemort from coming back in GoF? Etc. etc. I love stories about time travel but only if that's the driving force behind the story (like Back to the Future, Lightning by Dean Koontz, etc.). Otherwise, introducing that factor tends to muddle things up.
In any case, the time travel aspect of Azkaban always bothered me. I think making time travel a possibility in Harry's world was the single worst mistake that Rowling made in the series, because that leads to the question -- why didn't Aurors USE them to stop Voldemort before he gained power? Or, if they were a recent invention and they couldn't go back too far, why not go back and stop Voldemort from coming back in GoF? Etc. etc. I love stories about time travel but only if that's the driving force behind the story (like Back to the Future, Lightning by Dean Koontz, etc.). Otherwise, introducing that factor tends to muddle things up.