I had already completed V, VII, VIII, X and XIII. At that point I decided to finish the rest. I got through I, II and XII then moved on to VI where for some reason it's been a little trickier, perhaps because the story requires a lot more time than my bus ride home. It'll probably be easier when the sun goes down later - winter always makes me fall asleep on the bus as the windows are never open and the lack of fresh air makes me sleepy. xD