Always save offsite.
There is no exception to this rule. If you want to see the file again, save offsite. Get a DropBox account. Get an external hard drive. Get something!
Or, like me, sob because you were "going to back up later" and your hard drive just blew up and you've lost a week's worth of writing work, plus family photos, plus or miscellaneous files you thought you'd never, ever, lose.
My desktop is down. It crashed. It died. And it's going to take over $300 to repair. You know what that means: shelve it and save. With some careful spending I'll be able to afford repairs in October.
In the meantime, I'm running everything off my Ancient Laptop that is Older Than Dirt (or at least 3 of my kids) and trying to piece back together everything I had. I've lost passwords, bookmarks, chapters, outlines, entire books...
SAVE YOUR BOOKS!!!!
Because the Ancient Laptop is very ancient and prone to dying if you try to run it for more than a few hours at a time, I won't be online very much until I figure out a way around computer deaths. What computer time I do have I'm hording for writing. Yay! More books!
While I'm writing, go save your stuff.