Terry has written that at the advanced level, i.e. once basic structures have been acquired, internalized, then continued input builds vocabulary, collocations, etc. What I have found is that with languages I am reading, those in which I can find stories at the level I need them, my i+1 or thereabouts, promotes my reading far better than typical learners’ texts. For example, I have two introductory books for Dutch, one very simple and poorly done, the other a wonderful compendium of all sorts of Dutch. However, it is the first book I read b/c it has stories periodically, simple little stories about the little Dutch boy – just kidding – that I want to read to the end of while the wonderful book has dialogues of Jan on the phone arranging an outing with his friends or some such very boring material.
My own obsession with languages keeps me reading the boring stuff, but I sail through the stories. I’m reading a book that is a compendium and the chapters had typically 100 vocabulary words to learn! Having finally ploughed through a number of chapters with ok dialogues, I am reading essays on history, etc. now and the next volume is newspaper articles on a variety of topics. Very tough going initially.
In contrast, I am reading various items in Medieval Latin (Laura Gibbs published nice fables on line), novels in Spanish, etc., i.e. languages I know well enough to be able to read narrative, connected text in the form of novels and short stories. One language I know very little has cute stories heavily glossed while another language I know little of has dialogues – very boring. It is so much easier to read the stories than the dialogues.
My students in Latin read interesting and connected stories that are heavily glossed. If you read the stories over and over, as obsessed I do, you learn the vocabulary just by reading to full comprehension. But most people do not have that obsessive drive. So perhaps advanced texts of interesting stories could be the next step in tprs, at the level needed, which is not authentic, unedited text. At least IMHO.