I heard about a book giving detailed practice instructions on each one of the Chopin's Etudes...
Yes, there exist some publications concerning practical side of how to exercise the Chopin studies. As I suppose, you had heard about Alfred Cortot's preparatory studies to the Chopin's Etudes. Additionally, there could be found the famous Studies by Leopold Godowski and as well the introductory exercises to Chopin Studies by Aleksander Michalowski (1851-1938), former student of Karol Mikuli; after listening to his play, Franz Liszt said: this is how the pieces of Chopin should been interpreted! Prof. Aleksander Michalowski doubtlessly was the Greatest Polish Master of the Piano in his times. His most famous students were: Wanda Landowska, J. Zurawlew, J. Smidowicz, Misha Levitzky, J. Lefeld, B. Woytowicz, Vladimir Sofronitsky, M. Bar, Rosa Etkin, Wladyslaw Szpilman, Stefania Allina. Many composers and teachers who were the excellent pianists, too, have completed many different studies and other piano exercises: as Schumann, Brahms and Busoni.
These all training materials give many possibilities to improve ones piano technique - on the one, but very serious condition yet: one must know HOW to use ones hands, ears and fantasy BEFORE one starts to use them! Because, if played in the professionally improper way, these all preparatory, introductory and other exercises could cause only terrible pains and stresses - the physical and mental as well.
On the other hand such compendiums always presenting some new points of view on the piano technique and furthermore they might enlarge our instrumental horizons. Sometimes they can be useful, if searching for some special, additionally polishing technical habits.
Another category present the books and articles - among them I would like to maintain on the first place the famous Prof. Neuhaus' The Art of Piano Playing, but as well one might be thoroughly informed about many aspects of our art having a look at works by Abby Whiteside or Józef Hofman, for example. Unfortunately, there exist very many unnecessarily complicated books that have been written having as the main source of inspiration such piano pedagogic course as maintained below. Because I profoundly appreciate the Man, the citation is telling about, I would not like to put out his name herein. In any case he was one of the most famous and beloved virtuosi and the piano music composers in a whole history of the piano.
In my personal opinion this citation shows the method that, unfortunately, cannot produce any positive effect in the piano technical work:
"In order to make her hands more flexible and energetic, he had her study first of all certain passages that he considers very important. They consist of octaves repeated rapidly and for a long time on the same key.
With the exercise, he went through all twenty-four keys and the relative keys; he did the same for the arpeggiated octaves. He also wanted to hear chords repeated on the same tones, then octaves both simple and arpeggiated followed by trills with every finger while resting the other fingers on the keys, and, finally, repeated simple notes while again resting all other fingers. He does all this for hours on end, while at the same time reading to avoid boredom. This in the time, as he exercises his fingers, that he meditates over his reading".
This is how the real formalism in the piano pedagogy has been born. Unfortunately, I must say, such course - however equipped with very modern shape - again and again holds very powerful position in modern piano teaching, too.
... somebody might ask - why?