Criticism without solutions or suggestions makes a student feel like they're a lost cause. I've experienced criticism without concrete solutions. It makes you feel like giving up. There must be some encouragement to overcome the shortcomings. I believe assessment should always have one facet that outweighs all others.
Effort is the most important, especially in Art because it's so diverse of a subject.
The amount of effort a student puts forth should always be the most important requirement in any subject. Organization and planning are important parts in teaching also. A teacher must be organized so they are prepared for every class. The organization of a teacher rubs off on students. In addition, organization can effect classroom management.