Of course there are unlimited other ways to draw a shadow. The examples are just something to encourage experimentation and show you some opportunities.
The picture below shows you various drawing techniques exemplary used on geometric bodys. There you can see how different hatchings effect on the viewer.
At best you try to draw different techniques on your own. Simply try out a lot of things and don't stop to experiment. Have fun learning to draw!
There are a couple of ways you can create smooth shading across your drawing. The first of the pencil drawing techniques is to use your pencil to create smooth strokes close together. It may help to use the side of your pencil as you’re creating your lines. Start with your hardest pencil creating light lines with a varied starting point. Continue to darken your values by pressing down slightly harder and changing to a softer pencil. You want to try to keep your lines as close together as you can to create a smooth effect.