It's interesting to see different school's retake policies for test and summative work. In my high school, each department has similar but slightly different reassessment policies. For my department (math), each student is allowed to retake each assessment one time to earn full credit back. The new assessment has similar standards but different problems. When students reassess, they only need to demonstrate their new learning on the standards that they did not show mastery the first time and thus do not have to retake even the whole assessment. Prior to any reassessment though, students need to make the necessary corrections to the original assessment, have completed any formative work associate with that unit, and have a conference with the teacher. The science department allows one free reassessment per semester. If students need any additional reassessment, then they have to work out a plan with the teacher for additional help, practices, behavior plans, etc depending on the situation.
I do believe that reassessment is a good practice in that we ultimately want students to learn and apply our content whether that is the first chance on a test or two weeks later on a retake.