My backup "strategy" is very simple! The backup zips all my key stuff into a file with the date in its name. Those just sit on the fileserver's HD until I tidy up. I keep end-of-quarter for ever, end-of-month for three months, and so on. It's enough for me. For a large corporation , it would be no use at all.
Year-end accounts have their own filenames, and are stored on the two PC hard drives AND on floppies AND in printed form. Needless to say, I've never had to go back and use them.
The problem will come when I have a HD crash and can't find all the software to reinstall. So far, my CDROM filing system hasn't let me down.