Backing up your device regularly is strongly advised. Especially before a service. Each year our staff deal with several thousand customers who have lost everything on their devices. Not just email and documents. But photos and videos of their loved ones and many other precious memories, simply because they did not have a backup.
Data backup is exceptionally easy when done as a preventative measure. However, it is exceptionally expensive if something goes wrong, and you’re not prepared. In 70% of cases, when the drive fails, all data is lost, and no amount of money will bring it back.