In some photographs it is the shadow that makes the image. The shadow may not have substance in the real world, but when it comes to photographs it sure does. next to a big white area, a big black area has the most impact. It's important for photographers to think of shadowed areas as being real compositional shapes compositional elements when 'designing' an image, just as we would approach shape from the other side by reminding ourselves that a rock is actually a rectangular block of gray in the image.
Thinking of shadows as a real shape means that the photographer should pay more attention to the shadow. They are amenable to both moving around in space and in time, and on days with mixed sun and cloud, it's even possible to vary the density of the shadows by choosing the exact lighting you want.
In addition, blending multiple varied exposures can open up shadows by recording a longer dynamic range. Sometimes we actually want to deepen a shadow to give it more substance.
As an exercise, how about going out one day in your neighbourhood and simply walk around taking pictures of shadows. You may include the real thing or not, but the shadow is to be a main part of the image.
How about hauling out a variety of your favourite books of photographs and look exclusively for interesting shadows. Now go through your best work and how often do you take advantage of shadows or use them as major compositional elements.
The next time you go out on a photographic excursion, as a last check before pressing the shutter release, check for shadows, good or bad. Perhaps you will see a better way to arrange your picture.