Mostly I turn mine off (standby mode) Sometimes it goes into autoshutoff mode first.
Nice thing about it is that when you start it up, your right where you left off.
I watched my dad read backwards for years. As he started to fall asleep while reading his grip would loosen, and the paperback would flip back a few pages. He'd snort, wake up, read a page or do and repeat the process.
Being able to set when the auto shutoff kicks in is nice.