/ic/ - Artwork/Critique

What do people here think is the optimal ratio of reference to imagination. I've worked on the assumption that trying to draw something from imagination that you haven't studied before is simple poor practice and the ratio of reference to imagination should shift from mostly reference to mostly imagination as you gain proficiency. Right now I mostly draw from reference but when I occasionally draw a figure from imagination I do feel like I'm seeing similar progress as when I do from reference.