Several hours apart

I had decided to do some still life charcoal drawing. This is mainly due, I think, from an Edward Hopper drawing I recently saw. I drew the first take in bright sun of the afternoon. I was less than pleased with the results, but it was more than not doing a drawing. I came back after a few hours and a subsequent sunset. The scene was then lit by another light source. Without getting into the results I liked the set up much more than the first one and went back in. What am I supposed to be taking away from this? Lighting is important, its okay to go back in and I need to draw more. r.