The problem with mixing tools is that they work like water. When reapplied, it becomes even worse. And need to do as chorcoal and finger work in reality. He rubs the image and does not blur it, which gives control over the picture. The speed and efficiency of the work increases, and you do less action.
I think the algorithm of the tools is different. I learned all the tool settings. I set small and large values in the settings, use the texture, the effect is the same. To understand better you just need to paint with chorcoal and smudge with your finger. And draw in Photoshop with a mixer brush (smudge tool). You understand the difference, rubbing the chorcoal with your finger we get soft controlled transitions.
Below is a video for comparing the traditional artist and mine.