Personally I feel reluctant using that approach, as Urban Sketcher I want to make a snapshot of reality. My objective is not a nice painting as finished product, but my personal record of what I see.
So, in order to use the "values", "interesting forms", "silhouetting", "colour relations" etc., I had to find subjects that already had those elements in place. And that was very difficult. This is one of the very few places where I succeeded to find it, a barn in the hamlet Reilhac, found during a 10km training around the camping site. Even though I adapted a lot of forms in this sketch, at least I tried to keep the final image close to what it looked like for me.