A lot of instructors struggle to develop an appropriate amount of feedback to students, often straying in the direction of too little or veering off on the opposite tangent and providing copious amounts of feedback. No doubt, a lot depends on the kind of assignment (free write, in class prompt versus a formal, twenty-page research paper. But an important point to always remember is that if the student does not read, understand and learn from feedback, then the feedback is pointless.
Since I deal mostly in the online world, it is double critical that instructors get the feedback equation correct. I'm going to try out a MOOC in a few weeks on Performance Evaluation in the Online Classroom with the hope of finding some quick resources to be able to share with instructors.