My experience with masks so far is that they always seem very rough and not good looking where they end when it comes to sculpting the area near the edges of it. even with Dynamic Topology on the sculpt still looks odd. Will the course at some point explain how this can be smoothed better?
I feel like the lighter area will have a amount of give to help this become smoother, would this be correct?
Generally speaking you can always smooth your masks by pressing A and dragging your mouse to the Smooth mask option. This should help with a smooth falloff between masked and unmasked areas.
But if you post an image of the kind of rough result you're talking about then maybe I could offer more specific advice.