"Need" is in the eye of the beholder.
There are those who are comfortable recreating a system from scratch. I
keep thinking of those who never do this kind of thing and wing a V3R6 to
V7R1 migration without bothering with silly migration instructions and
whatnot. And then ask questions as to why this stopped working, guest
accounts are disabled, shares are all hosed up, WAS configurations are
lost and a host of other stuff.
Then there are those who like to do the raw restore from the monthly or
quarterly backup and then restore the other objects from objects stored on
Some document that as to how to get stuff like user profiles,
configuration changes, etc, back in sync.
Some insist on no longer than a week without a full system save.
Some are quite happy they only run first shift and can do a nightly full