I think it is important how a painting leads the viewer around the painting by how the shapes, values, colors, line and their placement are designed. That is not to say I am always successful in doing it all the time. Also sometimes a painting can be viewed like a stage where there is a star and costars and the placement of those characters can be important so that the eye is always brought back to the star but appreciating the costars in the process. We could and do sometimes paint shapes just for the beauty of the shape but even then that shape can have been designed in such a way as to make the eye travel back to the point of interest.