The ship has long since sailed on this point, powered on or not. There's research that's talked about in the book, "Data and Goliath" that explains how the beh

The ship has long since sailed on this point, powered on or not. There's research that's talked about in the book, "Data and Goliath" that explains how the behavior of people specifically trying to avoid being tracked is sufficiently different from most other people that, even if you turn off your phone (sometimes ESPECIALLY if you turn off your phone) that act can be a behavioral marker used to correlate your activities with other people who do similarly, and your location can be largely deduced by process of elimination anyway. It's a fascinating read.