Snippet: New Touch ID Rules ☇
Glenn Fleishman for Macworld:
When iOS 9 was released, Apple updated its list of cases in which iOS asks for a passcode even when Touch ID is enabled. A previously undocumented requirement asks for a passcode in a very particular set of circumstances: When the iPhone or iPad hasn’t been unlocked with its passcode in the previous six days, and Touch ID hasn’t been used to unlock it within the last eight hours. It’s a rolling timeout, so each time Touch ID unlocks a device, a new eight-hour timer starts to tick down until the passcode is required. If you wondered why you were being seemingly randomly prompted for your passcode (or more complicated password), this is likely the reason.
I think this is a good move, as it not only forces people to actually remember their passcode, but it also increases the chances that you’d need your passcode to unlock a device that has been sitting around for a bit. This may be beneficial in areas where you are legally forced to use your fingerprint, but not your passcode.