You have the ability to control all the periods at the sub-levels. You could for example, ensure that a subject is never the first or the last period of the day for all grades:
You can cater for the Headmaster or Heads of Departments :
You can cater for Part-Time educators:
Possible other uses include blocking a room at certain times or forcing P.E. Classes to take place the period before breaks and home-time to allow the learners to shower.