Interestingly, the charge rate across the
entire curve sounds like an important metric but in practice it is nearly irrelevant.
If you drive an ICE car, you are used to filling your tank. Because once you've gone through the trouble of driving to a gas station and pulling out your credit card and unscrewing the cap, well you might as well top it off, right? Life is different with electric.
You might know, for example, that most Teslas operate day-to-day with their max battery charge limit set around 80% or below (it extends battery life). Charging at night is entirely effortless, so you put the charge into the battery that you'll need for the next day, or like me, you set it to give you 4x your daily commute and totally forget about it. Only before a particularly long road trip do you pop open the app and slide up the charge limit.
For Superchargers, the model is a bit different because this is charging that's happening on-demand while you wait in the car or are off getting a bite or whatever, during your trip. The best measure is to examine the portion of the curve that actual drivers spend actually charging their cars at an actual Supercharger. So here we have it;
"V3 Supercharging will ultimately cut the amount of time customers spend charging by an average of 50%, as modeled on our fleet data."
So this is truly an average of 50% faster, for actual Tesla drivers. ICE-age drivers who love to hate Tesla will insist you have to integrate the charge-rate curve, but as usual they will be entirely missing the point.
Tesla could spend an atrocious amount of time and money improving charging speed from 90 to 100%. That might be how you charge your phone, but it's actually not how Tesla drivers charge their cars (or how the onboard guidance computer will plan to charge your car when it sets the route for you), and would have almost zero benefit for the Fleet. Charging en-route is most efficiently done to boost the battery up to 70-80% and then you get going again.
Supercharger deployment, at least in the USA, is modeled such that there are almost no trips where you would benefit from, or need to, fully charge at a Supercharger, versus making two charging stops which would add up to less time charging, and driving out of your way to the charger, overall.