Need Task durations to update automatically when tasks are completed

We need Wrike to be more agile. We have pre-determined durations for each task, but sometimes they are completed early or completed late. It would be helpful if the due date would collapse or extend automatically when the status was changed to completed. And subsequently, change all remaining task due dates, pull them in or push them out. Right now we have to manually adjust each duration when completed so it reflects when the task was actually completed.