Does Simple Overwrite 1 Pass Work?

I recently downloaded Recuva to amongst other things check on the operation of CCleaner. As a test I deleted a range of files and cookies using the "simple overwrite 1pass" setting in CCleaner. When I checked with Recuva I found that a large number of the files and cookies, I would say 80%, were classified as either "excellent" or "good" and no overwrite clusters were found. Does this mean that these files were not overwritten?