I turn off almost everything that I'm not specifically using. If I need GPS for navigation or something, I'll turn it on. Otherwise it stays off. I think some apps can work without GPS because they don't need a location as precise as GPS gives and can make do with location determined from WiFi and/or cell towers. I'm not sure, but IIRC, most apps I have that need GPS access will tell me that if my GPS is off and remind me to turn it on. Ones that don't probably don't *need* the GPS to function. But I am just kind of guessing here.