Our teachers cannot teach more than 6 lessons consecutively

You can specify a global value in menu Timetable - Parameters:

If this value is set to 6 then your teachers cannot teach from the 1st to 7th period in a row, but they can teach 1st and 2nd, then pause and then from 4th to 8th.

If you do not care about the consecutive lessons and your teachers can teach or shall teach more lessons in a row, just disable this option.

You can also specify this maximum consecutive lessons for individual teacher (the global value must be set first):

See also:
Teachers can not teach more than 3 consecutive periods without counting Planning time