Short version: Is it only running if the icon is visible in the status bar (I'm on 4.1.2)? THey used to say to only turn it on when you need it to save battery, but I read that doesn't apply to 4.1+, so leaving it on all the time wouldn't affect battery? Can it run when the screen is off (ie, some sneaky app sending my location without me knowing)? Longer version: I use Cerberus in case I lose my phone, and because apps can't turn on GPS like they could in previous versions of Android, I thought I should just leave it on all the time because I wouldn't be able to turn GPS on remotely if I lost my phone (I have since found that if you're rooted other apps CAN turn GPS on). I also use Llama (alongside Secure Settings), so I could set it to turn GPS on when I open Maps, My Tracks etc and then turn it off when I close those apps. Is there any point in going to all that effort, or should I just leave GPS on all the time? THanks.