So what's the right thing to do for them when they've done everything, or there's nothing to do? It would be neat if we could select against the evaluations with this user, and get the count of required submissions, then compare that against self.rubric_evals.must_grade to determine which of those cases we're in, and then give the user a nice piece of feedback one way or the other.

The simplifying assumptions I'm making of course are that self.rubric_evals.must_grade is set, and that all evaluations are peer evaluations. But I think we could assume that until the end of next sprint at least. :)