This calculation runs once a night only and recalculates every group and recognition. It will only process groups that are not locked and only active recognitions. Night Batch calculations will only occur at the defined time (by default 2am).
Apart from Night Batch calculations, only groups and recognitions defined as Recurring from scheduled time onwards will be recalculated if they meet the criteria.
Tip: A common reason to recalculate a group every day is a 'Birthday' group to see whose birthday it is today.