The general rule is that you should get to the outer lane once you are at the exit previous to yours. If someone stayed on the outer lane the whole time and you

The general rule is that you should get to the outer lane once you are at the exit previous to yours. If someone stayed on the outer lane the whole time and you have to cut them off, it's their fault (obviously, you still have to pay attention and let them pass if you can't cut them off safely, but they are the problem, not you).