Days in the sumamry line (I don’t like calling them tasks because they are not actually a task) are not additive. It is the working days between the earliest start date of any task in the sub-group and the latest finish date of any task in the sub-group. If for example there are 10 tasks in the group of 10 days each that all start on the same day and all finish on the same day, the total days will be 10, not 100.
Roll up groups above indented groups follow the same logic.
