I personally believe more time is needed for teachers to look over student work (and that would have to mean less class time). (teachermagazine.com.au)
Why young kids need less class time — and more play time — at school. (liinkproject.tcu.edu)
Historically, most schools in Germany started early but excused students by lunchtime, which translated to less class time for German students when compared to other member countries of the Organisation for the Economic Co-operation and Development (OECD). (edutopia.org)