Proust also used the notebook method of writing; and his notebooks were as chaotic as those of Agatha Christie. The French equivalent of "Notebook" is "cahier." His cahiers can be described as "a confused jumble of passages crossed out, revised, rearranged, and perfected." This shows that chaos is more typical of this method of writing than one might think.
What is perhaps most interesting is that he also named his Notebooks and referred to them by name. Some of these names were: "Fridolin", "Vénusté", "Querqueville", "Dux", "Babouche", "cahier vert", "gros cahier rouge", "petits cahiers Kirby Beard". The names provide a method of cross-referencing entries which might otherwise be difficult to find.
1. See also Mary Gordon on Handwriting.