Specify how many lessons shall be before certain position
You can create special card relationship that defines how many lessons shall be before certain position.
For example this picture defines a cardrelationship for all classes that have 1,2,3 or 4 biology lessons. For these classes the generator shall always place at least 2 lessons before 4th period:
So now there are at least 2 lessons of biology on good positions.
For classes that have more Biology lessons per week you can specify another card relationships.
See also:
Max one history lesson on 6th-7th position in each class (solution 1)