Old Bicycle Watercolor Painting - 15 x 20 inches

Painting this old bicycle watercolor is really fun.  It is complicated in a way that many of the areas are divided by lines either from the background or the subject itself.  I have tried to paint the shadow using layers of watercolor wash starting off with light mixture of French Ultramarine Blue and Alizarin Crimson.  Then after it is completely dry, another layer of the same mixture is added on top.  Then I added Windsor Green to the watercolor mixture to get it into a darker shades of grey.  Another two layers of this darker color is painted after the layer is dry.  It takes about six layers of watercolor wash to get to this stage I have show above.  I need to darken the shadows but come to a point where I need to ask myself what color of dark do I want with this.  The background was a white painted brick wall covers about two thirds of the wall and the upper part which I have not painted yet is a color of red brick.  Shoud l leave the shadow alone now and paint other areas first.?   I finally decided to leave it, look at it and think about it before I go any further with my old bicycle watercolor painting.