All backup routines must balance expense and effort against risk.
Each organization needs to decide how much work it is willing to risk losing and set its backup schedule accordingly. Database and accounting files are your most critical data assets. They should be backed up before and after any significant use. For most organizations, this means backing up these files daily. Nonprofits that do a lot of data entry should consider backing up their databases after each major data-entry session. Core files like documents (such as your Documents folders) and email files should be backed up at least once a week, or even once a day.