You would think we would know but I hear artists ask this question all the time. I have asked myself this same question.
It's because we want to know that it is complete and it is perfect. Or as perfect as it will be? That leaves open that you could darken that bird's wing, or add a background.
The FINISHED artwork here is from a series: Ohio (Cardinal and Carnation) See society6 collection here: United States Birds and Flowers