Lesson can be only once per week in certain classroom

For example you have two Gyms at your school. Big and small. Unfortunatelly these are not enough to accomodate all your Physical Education lessons, so in some cases you allow the Gym to be in the cellar in the basement.

But of course you want to minimize this.

So you can simply say that this room can only be used for example 5 times per week:

Notice the 'Apply Globally'. This means the max 5 is applied to all the PE lessons at your school.

So this way you have limited the usage of the basement room to necessary minimum. However it can happen that even though this room is only used 5 times, it maybe that one class have all their lessons in this basement room.

To fix this you can add next cardrelationship that will say that each class(or group if your PE is divided into groups) can have max 1 PE per week in the basement:

Now each group has PE max once per week in this emergency classroom and the room is used only 5 times per week in the whole school.

Notes:
- once you genererate a timetable you may try to harden the constraints and try max 4 per week.