Painting lessons in class must have gap at least 2 free days.

The software distributes lessons into timetable automatically according card distribution settings in subjects constraints. See this: Modifying the default card distribution per week for the subject

However, in case your timetable is for more days in a cycle (lets say 7 days), it may be required for some lessons to be "not very close" to each other during the week and its cycle (so you consider also last and then first day again).
Let's say, we have Painting lessons, which are two times per 7 days week timetable. In 5th grade classes you require these lessons shall be at least two days apart AND you wish that there should be gap when week repeats. So you can use this advanced card relationship:

Note
- If you just wish to have not consecutive days for two lessons from the same subject in a week, you can use either "ideal/no consecutive" card distribution for this subject or advanced relation "max consecutive days" = 1.
- for maximizing the gap of free days, you can use advanced relation "max free days between cards per week"