The selections vary from text to text.
Some works (esp. short stories, poetry, and speeches) are included in their entirety. The Blue Hotel is in its entirety. The Bierce book in the SERVICE Series contains several short stories.
Other books contain key selections from larger works. For example, in the Notes on Nursing (Mouse Book edition) we chose four long chapters. We find you can get 80% of what a book is about - and a distillation of an author's style - from a well-selected episode of a larger work.
The goal is to get access to the core elements of storytelling of the author. If you find that you like a smaller episode that is part of a larger work, you can (and should!) go get the full book. You could think about this as listening to individual tracks without having to listen to an entire album.
In each case, we make sure the story can sufficiently stand on its own.