I was doing some quick poses yesterday, thinking about drawing the shadow shapes with the brush. Each major chunk of shadow should have its own temperature gradient. Think like this: Sketch the contour>Draw the major shadow shapes >Spot in some contact (cast) shadows….and done! 15 and 20 min sketches.
And here’s the warmups from that session. You can see some of that ‘draw the shadow shapes’ in the faces I think.