Perhaps BlackoutPeriods is more suitable for your needs? I see that the example in the documentation of that parameter is more or less fitting for your case:
$Conf{BlackoutPeriods} = [
{
hourBegin => 7.0,
hourEnd => 19.5,
weekDays => [1, 2, 3, 4, 5],
},
];
If you want full backups to take place on the weekends, you can define the period for them at 7 days, and then manually trigger a full backup on a Saturday. The consequent full backups should automatically happen every Saturday after that.