On my HTC One V (Android 4 Ice Cream Sandwich), I can use "Settings / Security / Lock Phone After" to set the time, after which entering the PIN is required to unlock the screen. The maximum setting here is "15 minutes".
Practically, this means I have to enter the PIN every time I take the phone out of my pocket, too often for my liking. Can I increase this time span to something > 1 hour?
PS: I have encrypted my phone. I understand that I am taking a risk, when someone should steal my unlocked phone.