For those 1st stream and famous kindergartens where make no difference of number of students in AM or PM class because their seat always fully book. Like as SHK, SHCK, ST PAUL'S, ST. CAT., KV, MS, HY, GH etc.
Totally agree and want to add one more good point for pm class:
Much better teacher-student ratio for pm class than am class. In my kid's school, there are 28 students in am class but only around 18 students in pm. Same number of teachers in class. The smaller number of students in class can allow more small group discussions and enhance students' participation in class.