Before I left my host caught me and passed my my USB stick, saying you might have forgotten this. Now in fact I had forgotten it, and thanked them for their thoughtfulness.
What they did not realise was that I had written a thousand or so words and they had not "safely removed" the device.
I suspect the cache was written anyway.
But fortunately I had posted the written content to a blog anyway, so it would be possible to recover if I needed to.
Just one example - there are many - basically one backup leaves you a bit open - you need multiple stratgies and you still hope you never need to call on any of them!