After valuable feedback, I tried again with singer Dani Filth. My goal was sketching fast but still keep the important information readable. Important for me was that the basic head shape becomes visible and the distribution and proportion of the facials can be recognized. After trying different head shapes I stick to the squared shape and tried to make it more recognizable. All together I spend about 25 minutes on this exercise now. I looks pretty messy but I want to work it out later and for me it is understandable.