Earlier quoted context omitted.
You can go from east to west coast in the US in 10 days while limiting yourself to ~210 miles per day. For a retired person with little need to hurry that's reasonable even with only nightly charging. Personally, I have little interest in driving 600+ miles per day making fast charging minimally useful.
The big long range use cases in California is San Jose-Tahoe (with its mountain climb reducing range), LA-SF, LA-NV & SF-SD. So you would want a supercharger for those trips. Also for car commuting in big metros, 40-60 mile one ways are common enough, which is 120mi round trip. The previous generation of affordable EVs had 80 mi ranges, which didn't work for those metros.
However, I still think ~300 miles as the practical minimum because I do take longer trips and know I would occasionally forget to charge sometimes.