I have a problem with "nighttime driving" being a measure of good/bad drivers. We have one of these devices in each of our cars (Not Nationwide) & while hard braking, fast acceleration & nighttime driving are somewhat* valid measures of accident risk, nighttime driving is a silly measure for the purpose of this article. Getting off work at 12pm (which my son does) does not mean he's a bad driver, it means he drives at a time of day that has a higher risk of accidents. Despite almost 25% of his driving is between 12 & 4 am (the metric used), he's getting the best discount of all of us.  

*Which brings me to my next point - if you are a freeway commuter & must travel at rush hour, guess what? You will have quite a few rapid accelerations recorded because that's what the metered ramps require you to do. Go from stop to merge with 55-65 mph traffic quickly.  When some idiot suddenly changes lanes without signaling, you'll brake hard because YOU'RE a good driver reacting for safety.