Is it possible that a teacher free period either period 5 or 6 any one ?
Constraint teacher max 1 hours daily in hourly interval [5, 7).
Is teachers free periods details are available in FET. for example a teacher Mr. X 2 slots free per day ( mon 3,6 --- tues 5,4) etc .
If you generate the timetable you can find the an "index.html" in the results folder.
Click on that file and then choose the "teachers free periods" (if you use html level 5+, then you can move the mouse over a name and all his periods will be high lighted) and/or the "view statistics teachers" (here you can see only the number/value).