I had gotten into a bit of a flow with the Aubrey-Maturin books by Patrick O'Brian. They go on a mission, there are battles, Steven has some spy shenanagins he does, Jack looses some money, Jack gains some money, they go home, repeat. That is in no way a criticism.
But O'Brian was ballsy enough that in Reverse of the Medal, the eleventh novel, he threw out his immemorial customs and did some very different things with his characters. Plotlines that have been building up over several books come to fruition with major changes for our heroes. This book has made the series truly great. Very highly recommended, a 7!