Students are most concerned about the correct answers on a test immediately after the test. If you wait too long to return their papers, they are no longer concerned with what the correct answer was but are now concerned with how many they got wrong and why their answer is not correct. They no longer care about anything except the almighty grade. So when deciding what needs to be done immediately, returning the test to the student is right at the top of the list. If your class only meets once a week it becomes necessary to be clever and get those papers back before the next meeting. Otherwise be prepared for lenghty arguments over why their answer should be worth an additional point or two.