I only delete things when I'm sure I really want to delete them. Today I went to Finder -> Preferences and checked "Empty Trash securely" so that's now the default. But since I had never even paid any attention to the "Secure Empty Trash" option until recently, it might provide a bit more drive space if there was another option to really delete everything you had ever deleted, or securely empty everything that had previously been insecurely emptied.
