With 6 subjects it is probably not reasonable to expect too much each night in any one subject. On the other hand, most courses do not have associated homework each night, and without homework probably nothing will be done by most students. I don't think that it does much good, even with the advanced students, to tell them to read the chapter and think that they will do it, except for a few. The important thing would be to structure the questions so that they would be easily graded to avoid a mountain of paperwork. This way the teacher has variety and does not have to teach the same content for 6 periods and also more time allows for more labs and more in depth work.
Teachers also get more time to grade etc.