Ron put an image of his hard drive on a thumb drive, and when he tried to restore that image, there was a corrupt file that wouldn't let him proceed. He had to restore from a backup he made 3 months prior to that one. Leo says this is why having a secondary backup for data is such a good idea.
Imaging is a good part of an overall backup strategy, but it's important to have a backup he can look at and see each file. An image won't work like that. Images are great for backing up the OS and programs in the case of a drive failure, but data is best backed up to an external hard drive.