"I had not realised it was standard practice to leave GPS enabled at all times, must be getting old."
Indeed. I don't really understand the logic of leaving every bit of wireless shenanigans you can constantly enabled, and then complaining that they're actually being used and running down your battery. It takes maybe half a second to enable GPS or wifi or whatever, you simply swipe down to get the menu and hit the relevant icon. Any meaningful use of those services takes far more user interaction than that anyway - typing something to search on maps, entering wifi passwords (you're not letting your phone connect to every open wifi network it sees of course), and so on, so it's not like you're adding a ton of inconvenience. Leaving them all permanently enabled is just utter stupidity with no benefit to the user at all.