I'm only talking about rough sketches, very short, maybe three or four paragraphs. The material in and of itself is not something I would even want use in the future. Think of it as an artist's sketch pad; I practice (1) the purely technical aspect of my writing (2) my ability to quickly convey ideas (3) I consolidate information that was previously floating about in my skull into a nice package by anchoring it to a single event.

It's much the same with guitar or visual art (a least for myself): I may work creatively on one technique by using it to write some nice riffs on guitar or I may try to consolidate the technique of pointillism into my repertoire by using it to draw a face or a land scape. The outcomes of each of these mini-studies is not an end in itself, but rather a stepping stone to mastery.