I want to have 1+1+1+2 OR 1+2+2 lessons per week.
If you do not know the distribution from the start and you want to computer to decide you have to do it like this:
1. Define that you have 5 single lessons per week.
2. Define a card relationship like shown on this picture:
See also:
There can be two maths on one day, but not consecutivelly
There can be two math lessons on one day, but they need to be placed consecutivelly