Another point is that not all task/moduls are "mapped" on days of the week.
So in week view it makes sense, not in day view..
If this should grow into a student-planner, the student must be able to say (inside the span of a week) "This will I do today, that tomorrow, that the day after tomorr...with a max. of seven days if he does this on the first day of the week, If he starts to plan the next day he gets only 6 days in that week, then 5,4,3,2,1 and then NEXT WEEK.... etc...)