Here's a very useful top-tip that I found to be extremely helpful in drastically increasing the accuracy rate on the Samsung fingerprint sensors.
Unlike the sensor on the iPhone and Nexus devices, the sensor on the Samsung phones have an oval shape.
The trick here is to not just have the scanner learn your fingerprint in one direction. Instead, change the direction of your finger between every step of the learning process. Either move it up or down, and even change the direction of where your finger is touching on the button. Do it in a way that allows as much of your finger to be learned by the sensor as possible.
I tried that on a Galaxy A5. Previously, when setting up the sensor in a conventional method, the sensor was hit-or-miss, with about a 70% hit rate. That's not downright horrible but not good either. After retraining it using the steps above, I found that it has gotten much more accurate with a 90+% hit rate.
I did the same on my Note7 and it also had the same hit-rate, although mine is rather sensitive, as it trips easily at times when my fingers are wet.Another bonus is that after an OTA, the speed of the sensor increased drastically. Pressing the home button to wake the phone automatically unlocks it, just like the one on the iPhone 6s.
I've used Huawei fingerprint sensors too, and they are regarded as one of the best on a phone, so I know how a good sensor should perform. The Note7 isn't the very best I've used, but it's a very solid performer.