Saving a document only takes the use of two hotkeys on most systems: 'apple + s' on a Mac, 'esc + w' in <font color="blue">vi</font> on UNIX, and 'ctrl + s' on Windoze. I recommend using them whenever you've typed something you don't wish to lose. It takes little more than a tenth of a second to include that key sequence in the middle of typing up any paragraph and ends up saving everything up to that point in the document. You don't have to specify the name of the document when you do this ( afterall, it's not a 'Save As' command ). You don't even have to interrupt your typing - it will just save the update in place with the same name and allow you to continue on typing the document without so much as a pause. I've never understood why people still fail to save partial copies of what they are typing - it's a trade off between a tenth of a second worth of extra keystrokes and forever losing text that you may not be able to adequately reconstruct if it were to disappear.
Remember, data loss isn't about 'if' it will happen, it's about 'when'.