A parent task's duration should be a rollup of it's subtask's duration total. For example, if a parent task has 2 subtasks with task A duration 3 days and task B duration 7 days, the parent duration should be rolled up to show 10 days. Currently, my parent task will show an arbitrary number such as 2 days or something inaccurate and I have to manually update it.

This should function similar to the time estimate rollup.