|Flash drives are the least reliable of modern storage media and should not be trusted for primary storage of important files. They should be used primarily as a data interchange media where the data is stored on some other media, such as a hard disk.|
All important files, wherever they are stored, need at least one backup copy. Particularly important files need 2 or more backup copies. Having no backups is asking for trouble. Unfortunately, most people do not learn this until it is too late.