Art and Time Management: How many hours working? How much time spent on each drawing...?

On average, on the days I do spend an average amount of time drawing, my art workday lasts anywhere from 1 to 2 hours a day...

Upon timing myself with a stopwatch, most of my really good art takes 40 minutes to 1 hour per drawing to do...

Any more than that per day tends to exhaust, stress out, and fatigue me a bit, as I suffer from chronic fatigue, so I'm definitely not the hardest worker. I kind of doubt I have the physical requirements or capabilities to be the hardest worker in art. But I AM one of the most strategic.