In order to use constraints such as max idle weekends, you need to define how a weekend looks like through the weekend definition:
weekend FRI-SUN
{
  "options" : {
    "idleWeekend" : {
      "fromDayOfWeek" : "FRIDAY",
      "fromTime" : "19:00:00",
      "toDayOfWeek" : "SUNDAY",
      "toTime" : "23:00:00"
    }
  }
}
weekend SAT-MON
{
  "options" : {
    "idleWeekend" : {
      "fromDayOfWeek" : "SATURDAY",
      "fromTime" : "08:00:00",
      "toDayOfWeek" : "MONDAY",
      "toTime" : "08:00:00"
    }
  }
}