Most people don’t know that you can train Touch ID beyond the initial setup. Of course, every time you use Touch ID, it learns more about your fingerprint. I’m talking about deliberately adding lots of data, which increases performance — decreasing both false negatives and time to verify a fingerprint.
To start training, go to Touch ID & Passcode in the Settings app. It will ask you for your passcode to change Touch ID settings. From here, touch one of your added fingerprints to the Touch ID sensor. You’ll see the entry for that fingerprint is highlighted temporarily, which means it just recorded more data. Do this for a while, walking it to different parts of your fingerprint, and you should notice Touch ID start unlocking your phone faster than before.