There are only two times I use it:
1 - When someone leaves the company. Most of the time I leave their mailbox in place for up to 6 months. Then I export it to a PST, write that file to a CD and delete the mailbox.
2 - The only other time I used it was when I was doing a swing upgrade of Exchange and I had some users who had corrupted items in their mailbox and couldn't be moved using the "Move mailbox" function. I needed to export each part of the mailbox as a PST to find the offending items and then put the whole thing back together on the new server.
I do this so infrequently that I don't bother to script it. We are also a small company (~50 mailboxes)