The darkest darks in this image are approaching opacity. Any more pigment in the mix and the paper would be throughly masked. But don't back away yet! Some of the most beautiful passages remain to be laid down; the red barn, the warm grey fence and the cool grey window wall. There is still room to use color and value to contrast the shadows and the sunlit areas.
Too often we stop short of the real limit, thinking the paint will lose its sacred transparency. The demo this afternoon was designed to encourage you to deliberately broaden the range of what is acceptable . If you stay out of the water bucket your paint will get darker and thicker by definition.
You can experiment with how to use the fact that watercolor dries lighter than it appears. Make a wash of a powerful dark to cover the snow. Now add some super dark, made from pthalo blue and transparent pyrol orange, and use your homemade black to make the tufts of grass and saplings.
Here are a couple more to try. Make the darks as dark as you can , then make an even darker dark after that one dries. You should find just enough to make a layer that that is thick and dark enough to make profound depth but still fluid enough for the strokes to flow into each other.