It depends on the ability levels and the students' competence and knowledge of the English language and its conventions. In my experience in public schooling, there is always much variety in ability levels in a single classroom. Students may work at a variety of skill and concept levels simultaneously in an effort to foster classrooms that are inclusive. A student's chronological age may not match his/her ability level. There is no one-size fits all approach to answer this question. It is entirely dependent on each student's ability. In a perfect world with students of "normal" or comparable ability levels in the same classroom, four essays per semester seem reasonable.
It depends on the ability levels and the students' competence and knowledge of the English language and its conventions. In my experience in public schooling, there is always much variety in ability levels in a single classroom. Students may work at a variety of skill and concept levels simultaneously in an effort to foster classrooms that are inclusive. A student's chronological age may not match his/her ability level. There is no one-size fits all approach to answer this question. It is entirely dependent on each student's ability. In a perfect world with students of "normal" or comparable ability levels in the same classroom, four essays per semester seem reasonable.