The Employee that leaves
An employee leaves the company, you deactivate their Office 365 account. However, you need to retrieve an email, an Excel spreadsheet or a presentation from their account.
So what do you do - call Microsoft? Well they will tell you that from the time you deactivated the employees account they held the files for 30 days then deleted them.
With a cloud backup solution, you can recover all of the files (including emails) in a matter of minutes. In fact, you can search backups at a granular level.