Cottonwood
Roadster#433, Model S#S37
Also keep in mind most high amp L2 stations on Sun Country Highway are 208V 70A (14.56kW) which will increase charge times by 30% compared to 240V 80A.
The spreadsheet clearly shows the need for SuperChargers on road trips. With high amp L2 it's counterproductive to drive faster than 60mph - you'll spend more time charging than you save driving. High amp L2 is great as a destination charger, but doesn't cut it for long distance road trips.
Mostly, I agree with your statement. A favorite method of travel for me is to stay at a hotel with L2 charging available, that is within easy range of Superchargers. As you say L2 charging at a destination is perfect; charging while I sleep takes no time from me.
The one exception where L2 charging is useful, is for moderate distance travel. That is, where the total trip distance for the day (or between Superchargers) is slightly more than you can do in one charge. Having a good, high-amp, L2 charger about half way can make such a trip very nice. A good example, that I often do, is driving between my two houses in Pagosa Springs and Boulder, Colorado. They are about 300 miles apart. Salida, Colorado is about half way between the two, and I have worked with P.T. Wood, the owner and chief alchemist of Wood's High Mountain Distillery, to install a 70A, 240V J1772 at Wood's in downtown Salida. It makes for a pleasant trip to stop in Salida for an hour or two charge, talk to PT, have lunch, etc and then continue on to Pagosa.