In general I disagree. I posted comments paragraph by paragraph, hopefully not losing the big picture!
The approach will not be sequential (i.e. to work on some fragments for three weeks and then move on to the next set), but rather as simultaneous as possible (in practice: sample about 8-10 fragments, keep them for some successive days, then re-sample from the set of fragments [some fragments could also be kept], and to frequently re-visit fragments over time).
Neuhaus described Godowksy's method of practicing, and keeping a lot of repertoire. He would practice passages only, taking out this book, then that book, and often the passages would be mechanically related. In this way he was able to look at a lot of music in a short amount of time.
This seems to be similar to your proposal: to sample these little bits and maintain a technical level on all of them. I disagree, because Godowsky had already mastered the music he was sampling. In order to achieve mechanical mastery, I don't think you can work a little bit of time on a little bit of something every day. At some point, a difficult thing requires your full, undivided attention. Personally, when I encounter problems, I know that they have to be worked at until they are solved. Not a little bit here, then there; they have to be solved then and there.
But that is only my method. My main point is, little bits don't cut it. The only way to improve is undivided attention.
My questions are:
1. do you also consider this a promising approach of working towards the goal of playing all etudes at a very high level at a single point of time? If not, please share the reasons why you disagree, because I might reconsider the plan if the reasons are convincing.
I don't, partly because of the reason I mentioned above, and also because one of the challenges of each etude is the stamina issue. I get the impression that your approach is based on, once you understand the inherent problem the rest of the etude will come easily. There's a certain truth in that, but I think it is better expressed like this: once you understand the inherent problem, the
practicing will come easily. Each etude still demands an amazing amount of work.
Lots of people play all 12 or 24 or whatever at once, and I am sure if you are attempting it that means you can do it. But I find this "bits and pieces" approach to be too unfocussed.
1.) Here is why I think this approach might be better than just working on full etudes sequentially:
-- With only 30-40 minutes daily time (as I said, the rest goes into the transcriptions for the next months), it is not feasible to expect intensive work on all etudes and to keep them all alive and in steady progress for a long time.
It's definitely not feasible! I don't think it is feasible to expect to master 10 "fragments" in 30 minutes either. I think there's a weird contradiction of overly organized (practicing with distinct time limits) and also unfocussed (always moving on to the next thing because of time limits). I think one is better taking an entire etude, and learning it with undivided attention. For fun, one sight-reads the others, examines them here and there, but ultimately what is required is undivided attention.
-- By working on selected, representative fragments, we can work in very much depth on every little detail of motion and musicality (because in the end the fragments should be played as musical as possible, as they would appear in the full etude). Once the details are understood for the fragment, it will be much easier (at least this is the hypothesis :p ) to transfer this to the full rest of the etude.
Another thought I had is that in each etude, with each problem Chopin presents, he always presents it, in addition to in the clearest way possible, in a very problematic, almost awkward way. For instance, the opening bars of op.10 no.1 could not be clearer. But later on, there are some bars which are almost impossible to play without readjusting the fingering in some way (or some people even readjust hand divisions). A similar passage occurs to me in op.10 no.2, and op.25 no.12 (I can cite bar #'s later if you are interested).
I mention this to reinforce my thesis of undivided attention. Becoming mechanically acquainted with a problem won't be enough to learn the etudes.
-- In this approach, very little time is spent on "learning the notes". I quickly know all fragments by heart and we can focus entirely on the real stuff.
I've always found the notes to Chopin etudes, among the easiest in all the repertoire to learn, and the hardest to forget.
-- Most importantly, I will have practised all fragments for a very long time, and crucially with many and frequent revisits. This is also not feasible when working on the full etudes with the time that I want to devote to this.
I think you're better off using your attention to learn an entire etude, because let's say you practice this or that fragment over and over again, then have to learn the piece, and only the bars you have been practicing for 6 months or whatever sound good, and the rest sounds bad?
-- By working on other repertoire during this "preparation phase", I have enough diversity of styles and pieces to also cover other aspects of piano playing.
Well why don't you learn all your repertoire in this way? Why not, play all the first themes of Beethoven sonatas for so much time in a day, because if you learn the first themes to Beethoven sonatas, they are almost always building blocks for the whole movement, if not piece. I don't think anyone would do it, because they would recognize the way to be to focus on one Beethoven sonata, and learn it thoroughly!
I think I can understand your attitude towards the Etudes, and I have encountered it before, heard it before. Chopin organized them so highly and with such purity of purpose, that it often inspires us to try and do the same. But time is not as short as one thinks, and the hour spent in solid, undivided concentration is worth months spent on fragmented, time-conscious practicing.
2.) A caveat I have not mentioned above: In several etudes, stamina is a substantial problem for most people (10/2 being a particularly notorious example for many, including me). This means we also need to add some stamina exercises for these etudes, but they should also be derived from the same fragments (by repetitions or very simple alterations of a fragment) for the reasons listed above.
I have a better idea than inventing stamina exercises - play the whole etude!

Walter Ramsey