As I was painting yesterday, I realized how I was thinking of the painting in terms of "here is this building, here is a tree, here is the street winding away and disappearing". I wanted to think in terms of big value shapes and design, but it was not intuitive to me. It didn't help that I only had about an hour to finish my painting. (I also wonder if the fact that I was working on a small surface (7.5x11) is a factor, because there is hardly any real estate for me to think in big shapes? I am not sure about this one because James Gurney seems to be able to do such wonderful realistic paintings on his 5.5x8 moleskine.)
Anyway, I got thinking about this some more after I returned home and picked a few books off the shelf to flip through for ideas. Funnily, my previous bookmark in Tom Hoffmann's Watercolor Painting book led me to the exact thing I needed. In order to clarify the big shapes, Tom suggests breaking the picture down into large shapes (10 or less), and doing a five value watercolor sketch to understand the value relationships in the composition.
This is the sort of exercise I would always resist doing because I am always in a hurry to do a full painting, that is a final product that can stand on its own. I realize now, though, that to take my painting to the next level I need to step back, evaluate the areas in my painting that need work, design exercises to fix these areas and execute.
In that spirit, I did a bunch of these value exercises from some reference photos on Wet Canvas. Here is an example. I picked reference photos that already had good design in terms of shapes, so that I was only focusing on understanding the values and not worried about creating a composition.