Or to give a rather extreme example, I charge to 90% twice a week, and run it down to around 10%, and sometimes even lower, with a little bit of topping up at home (110V only, and a power-limited neighborhood that wouldn't allow me to put in 220V charging even if I wanted to). If I were actually limited to 80%, I would have to charge four times per week from about 40% to 80%, and because I would never actually reach the low state of charge where I would be charging at the fastest speeds, I seem to recall doing the math at one point and determining that I would actually end up spending
more time charging.
It's one of those situations where second-guessing customer needs will lead to wrong calculations and make things worse (not to mention more annoying), for no good reason.
Besides, if we're really having to worry about the difference between 80% and 90% — 60 minutes and 70 minutes at a V2 supercharger, assuming you don't get lucky and find an open pair — then we have much bigger problems. After all, even if you could reliably reduce everyone's usage that much, that only buys you maybe a few months of additional car sales before we're right back where you started.
The right fix is for Tesla to start upgrading their busiest V2 superchargers to V3 as quickly as possible. That's really the only sane solution to the problem. And while they're at it, they should negotiate to add more stalls at each of those locations. Ideally, they should start by adding one bank of 8 or 12 V3 stalls, then tear down the old stalls in groups of either 8 or 12 and replace them with V3 stalls. That way, they never have less capacity than they had before, and when they're done, everything is shiny and new.
