You're absolutly right Hive account@zanetaviz... This technique also provides the ability to create gradations that create direct structures (of the materials and upholstery) and also contributes to the general illusion of depth.
It's one of the many techniques of drawing, but for me, one who works perfectly.
So, I can only say, just give it a try... Start with easy forms and small drawings, because it takes a lot of patience to built up an image, so you can test if it's something for you.

Wish you a lot of fun with your experiments and warm regards!