After the phone restarts, you must unlock your phone with your PIN(or swipe pattern) before you can use your finger again. The same is true with the 24 hour timer. Android also has a feature that if you hit the power button a set amount of times, it requires the PIN/Pattern too. So if my phone and my finger print have been separate for more than 24 hours, my fingerprint is useless. If I have any warning at all, my fingerprint is useless. Also, after a set number of failed biometric attempts it requires PIN as well. Which means the law better get the finger print right in only a few tries or they lose their chance.

Yes, it is technically possible that law enforcement may steal my phone, duplicate my finger print(in a way that works on my phone's finger print reader), and use that to unlock my phone while they have a chance, then suck everything out of my phone. But for anything government, that's moving pretty swift for anything they might want to book me for.

I'm guessing you could reduce that to a lower number of hours if you really felt the need.