The result can be frustration and negative reinforcement. Effective feedback should be consistent. The feedback must build on the same themes and correct the same mistakes each time. Students compare the information they receive with their classmates to try to synthesize the information. Students also use each incidence of feedback to build toward the next project.
Effective feedback is consistent from both student to student and project to project.
Effective feedback should be comprehensive. The feedback must cover each of the criteria set out for grading. Grading only for analysis negatively reinforces writing skills. The more explicit the criteria, the more they are reinforced. Further, explicit criteria help students know what to study.