"When you perform a full save of your file, there is no way to go back to your original version. If the document was saved automatically, in many instances data would be lost because a full save is irreversible.
In contrast, AutoRecover does not overwrite your original file; this allows you to back out of most errors just by not saving changes when you close the file.
An AutoRecover file is created or updated each time there are changes that have not been saved at the end of the preset time period. You should perform a full save specifically based on progress you've made in your document rather than arbitrarily at regular time intervals.
NOTE: Another way to protect your work and maintain all of your changes is to use the Versions command on the File menu."