When you say unlock your screen do you mean swiping up the lock or do you mean using an pattern, lock pattern, facelock, or password?
I am a long time lock user, pattern, face, etc, and they are great except if you forget your unlock code. It's happened to me a couple of times I change the code that morning and that afternoon I've forgotten it. Anyway if you exhaust your attempts at unlocking the device you then need to provide your Google account information. However the thing is, even though you've entered in a hundred times setting up the phone, it has to connect to the network to verify your input. No network no access. It's really a scary thing. I'm not brave enough to try this to verify if this is correct, but I'm wondering if it turns on data to ensure that you cannot be locked out of your device?