Thanks for that.
What I'm actually trying to determine is this: Whether the battery-depleting behavior of Google Now is entirely curbed by turning it off in the settings.
That's the sort of thing Google's instructions rarely tell us, and my unfamiliarity with Jelly Bean and Now is the reason I don't have an answer.
Typical threads on battery life:
Hey, look, people discussing battery life in sleep mode!
O the overwhelming neatitude: Ordinary folks just like us talking about Jelly Bean and battery usage as we talk about their talking about it!