Stand On Your Head

Looking at a painting from a different vantage point helps you to see mistakes in composition and value.  I don't literally stand on my head, but sometimes I turn the painting upside down.  One of my favorite artist/authors is Lori McKnee and this article describes the advantages of doing that.  Turning the painting upside down allows you to see the composition differently.  Turning your head to the side can sometimes do the same thing.  Can you still see the focal point?  How does your eye enter the composition and move around?

Here's a work-in-progress, from a series of city scenes.  I can see the negative shapes of the sky better when it's turned upside down as well as how the composition is working.

My favorite method, though, of checking on how I'm doing is taking photos and looking at them on my computer screen.  I suddenly see mistakes in drawing or in value a lot better by looking at a photo.  Some artists use a mirror to do the same thing.  I don't really stand on my head (I never could do that!).  Do you use these methods to assess your progress?