To give you a sense of my painting process, I usual keep a limited palette, so I like to work on two paintings at a time. By blocking in the background, I'm able to let it dry, which is rather quick on paper, so that when I rework those areas, I can wipe off what I don't like. And it makes the painting easier to manage since an all-wet surface can get messy rather quickly.
What this drying time allows me is to see the parts that I want to keep somewhat rough and the others that I want to rework. While painting, I mix some colors on the palette; however I find myself these days keeping some colors distinct before applying them onto the paper, mixing them once they are applied. For instance, this palette had three different blues, a purple, and white. Once the sky was in, I then added three greens, using the leftover blue for shadow on the green areas. I blocked in the brown on the tree because I know how I'm going to approach the bark already, but I left the nest alone-- not quite sure. I don't love the house in the first one-- Tree House. It's off-kilter, so I'll have to straighten it out along with tightening up the free form landscape. As for the house in Bird's Nest, I like the drawing, so I'm considering making the brick color on the house less opaque and more of a wash.