I usually just use the first slot of the backbuffer, but it does come in handy if I delete an object by mistake.
I don't really use the other stuff that works with the backbuffer, like g gradients, shift+tab drawing, shift+f random fills, and the locking thing (/), but they can be useful. I use copy and paste more often (to shuffle things around).
edit
here are bonos pitucers from the same space project because I'm tires and should be asleep

i think hills with a sun in the back is becomeing a cliche from me HOW ARE YOU SUPPOSED TO SEE THE SCENE IF THE SUNS BEAMING IN YOUR FACE??? oh well
goodnight!