When you can look at a scene and see it as a series of layers made of washes and strokes, there is information there that might tell you when you need to be careful and when you can be carefree.
In this scene, for example, the small adobe building in the background has a dark line all across its top. That outline gives definition to the shape, establishing an edge that would show a viewer exactly where the top of the building is, even if the first layer had been painted very casually. Now look at the bottom of that same building. See how the dark shadow in the street defines half of the bottom edge of the building? And there's another shadow in the lower left corner that neatly establishes the rest of the border of the rectangle. These dark shapes that surround the basic form of the little building would make its presence very clear no matter how far "outside the lines" the initial layer had been painted. Even if it had bled into the sky with a soft edge, the darks would pull it together. Seeing this in advance would allow you to be quite carefree in the early stages of a painting.
"Why does that matter?", you may ask.
The less careful you need to be, the more attention you can devote to laying down gorgeous, juicy paint. When your brushwork is constrained by a narrow idea of "getting it right", the strokes tend to be dry and tight. Why put unnecessary limits on yourself?
Look again at the scene. Do you see any other opportunities to paint loosely? Look for outlines and edges of shapes that would give final definition to earlier layers. There are enough late stage lines and shapes in this image to dramatically widen the range of what will work in the first couple of layers.
With the color removed and the contrast exaggerated, it's easier to see the role the darks play in defining the edges of the shapes in the scene. If you imagine superimposing these distinct darks onto a playful underpainting of lights and middle values, it becomes clear when in the sequence you would need to get it right.
Here are a couple more images that leave the careful part for late in the process. Have faith. Take big chances.
The top edges of every shape in this scene are given most of their final definition by the last layer of strokes.
Here the middle value shapes require more care than the lights, though they are still quite simple. The darks look like they would clarify any sloppiness very well.