Every year when I teach Christian Heritage at Baylor (Church history and Theology), I always have students who are shocked that some aspect of their progressive church worship that they thought was new and innovative was actually practiced by this or that person in Church history. Take the small group phenomenon over that past 20 years or so. Well, sorry guys, John Wesley beat you to the punch on that one with his "classes" in the early Methodist church.
What about loud, free, raucous worship so often practiced in the charismatic movement, sorry, not new either. Try the camp meetings of the first and second great awakenings in America.
So, here is a good rule of thumb I think:
If you ever think you have a new good idea, search for it in history. It is not that new ideas don’t exist. New ideas come about all the time. But, new good ideas are very rare. If you think you have a good idea that is new, chances are you can find someone somewhere that has had it before. If it is truly new, it is probably not truly good, and if it is truly good, it is probably not truly new.
Unfortunately this goes for dissertations as well.