Paul Maloney has published an interesting article on Wpzine “How to Ajust Your Autosave Timings”
Paul says: “Have you ever been writing a post on your blog, and your computer has suddenly locked or you lose your internet connection and you have lost all of your article? Most of us have been there and if you haven’t experienced this take my word its upsetting!
WordPress’ default auto save internal is usually 60 seconds, you might want it to save every 30 perhaps? ”
The article include code to add to your wp-config.php.