Yesterday I had Sim chose training dummy over easel on home lot in home town, but that was insane neurotic computer whiz photographer eye and perfectionist. He had 2 level atletic and 3 level painting skill.
Except for taking photo of celebrity (which you never see in cell phone), I never saw them taking photos or painting portraits and still life - cause you have to control most of that action. I noticed once they chose one activity, they'll tend to do it all the time, if it is fishing, playing with sprinkles or swimming, or playing chess or painting, or drinking coffee. I also have situations when Sims will go continue writting novel, but never start writting new one.
Sometimes children would stay in front of the school and finish homework instead of coming home, but often will not finish it cause of low needs after school, or other distraction.
High level athletic Sim wil train others all the time ( I had 3.gen in dynasty torturing all immortals on treadmill).
When I find out more, I'll post it here