"In art a sketch starts with "animal lines", as you say about the unrefined design concept. But eventually it reaches a high point and importantly also, moving it forward to completion is key. "

"I agree wholeheartedly that sketching is very key, and besides sketching to verbally communicate your thinking. A sketch can draw an audience during significant events such as meetings when you might be called upon to expand on your thinking of a relevant or crucial design problem. Being able to communicate verbally in the moment what the intention of the drawing is very powerful.  A good and timely sketch, full of substance, can move an entire project forward."