important to note that In the Fall and Spring, teachers should test until the student reaches their placement level. Placement level is the level at which teachers have obtained enough information to determine a student's instructional needs.
My first thought as an ESL Teacher is how fast a student learning English may change levels, which can make a student's instructional needs change rapidly. I encourage classroom teachers to test ESL students again after he/she becomes more fluent with English and has adjusted to his new environment.