What does RIGOR look like in the art room?

At Ballou, the staff has recently started a professional development workshop series about rigor in the classroom. At our last meeting, we were considering barriers and bridges to rigor in our classrooms.
Barriers:
Attendance and truancy
Lack of materials, technology, and art supplies
Varying skills levels, and at least 50% of students have NEVER taken art before (don't know basics)
Not knowing special needs of students (IEPs)
Constantly changing class rosters

Bridges
Scaffolding
Art allows for personal modification to individual skill level

Aside from thinking about the bridges and barriers to rigor, I started to think about the question 'what does rigor look like in the art room'? In English, Math or Science it might be a bit more straightforward but what does a rigorous art class look like? After brainstorming with a colleague we came up with this list:
Rigor
1. Students directing artmaking and students making conscious choices about their artmaking subject and process
2. Students creating artworks that clearly communicate a message
3. Students being able to defend their artistic choices both verbally and in writing

What else do you think rigor looks like in the art room?

I always think it is a sign of a well run class when I can just sit at my desk and the students direct themeselves. When I design a lesson, I typically front load the lesson, meaning, we do some discussions, definitions, practice and sketching when an assignment is introduced and then it transitions into a couple studio days where the students work independently on their art. On the studio days, I am often happily bored, walking around the classroom observing student progress, asking them questions but generally giving them space to make the art on their own. I am happy when I am not needed on these days because typically that means I have already taught the lesson well- they know how to use the art materials, they have a design or sketch ready to go, and they can self direct with little help. Do you agree that this is a good thing in the art room? Or do you think a more rigorous lesson would lead to more questions and problems?