The decision to allow students to retake exams and every conversation surrounding it should be based on the best path for learning. Always remember that.
Lately, I was grappling with the question: "Is a full exam retake necessary and effective for each student whose score is almost perfect?" The question came up because, invariably, every class has those students who earn a 94% but still want to retake the exam and shoot for 100%. I will always allow this, but recently I was wondering if a retake is the best way to earn that extra 6%. I asked myself, "What would help this person increase his or her understanding from nearly perfect to perfect?" For such a student, I think retaking the exam is too mechanical, an trivial item on a checklist to achieve perfection. By contrast, I've heard it said you've never truly mastered something until you can teach it.