Not to be selfish about this whole idea, but the workload issue must be addressed. I find that I'm a less effective teacher under this system of retakes, because I am grading twice as many papers, retesting kids until 4pm several days per week, and writing new assessments when I should be lesson planning. I am with students from 7 - 3:30 most days - and that includes my lunch time, and then I take two hours of work home as well. I also devote at least one weekend day to work. Some of this comes from teaching a new class this year, but most of the work comes from the retake policy. Teachers that coach, and are thus not available after school are using what would ordinarily be instructional time to retest students. This is completely unfair to students who DID study the first time, did well, and are ready to move on.
Another issue that I find is that the grades no longer are very discriminating between excellent students, who really do "get it," and much slower students who only "got it" after several retakes. Both types of students get A's, but I find that the students who needed several tries have a much lower understanding of the material. They are learning to the test, not to the comprehension and connections that define "A" students. An A now means only that a student met the minimum competency required for most of the standards. Hardly exemplary.