Paintings and drawings are usually rectangles consisting of length and width. Depth is an illusion. Every square inch of the rectangle is part of a shape. The sum total of the shapes cover the rectangle. Pretty elementary when you think of it. How the artist arranges the shapes and gives them color and value determines the the overall effectiveness of the final work. Creating interest should be the artist's goal. Reduce the number of shapes, trap the lights or the darks and make sure the abstract patterns are interesting from across the room.