It would be nice if tasks (or subtasks) would automatically inherit the due date of the list (or project or task). Because there is no way these items have a due date AFTER the due date higher in the hierarchy. After that, if one wants to set a prior due date one could manually change due dates of items farther down in the hierarchy. Maybe when setting a due date (or in the general settings at that) one could be asked "should the items below inherit the due date?"