How should a Department tree Version be end dated in HCM?

We are looking for best practice information on managing structure changes in our Department tree. We've decided to update the version when we make a change that affects the structure and can see that an end date can be added when in draft mode.

I would like to know the purpose and impact of making the tree version inactive - does this mean that any Areas of Responsibility set against the tree will not be valid for the period that the tree is now inactive? If we can start and end date the tree version does it need to be made inactive? How does making this inactive affect reporting when looking at assignments against department hierarchy?