could a charging site have a buffer of fast charging batteries?

Yes, but have you ever seen 8 queues of cars, about 8-10 cars in each, at Sams Club or Costco buying gas? You'd need a awful lot of battery buffer to keep up with that kind of demand. At some point you'd deplete the batteries and be stuck with charging at whatever rate the grid connection could deliver.

	▲	Toutouxc an hour ago \| parent \| next [-]
		First, that exact situation simply doesn't have an equivalent in the EV world. Quite a lot of people should be able to charge elsewhere (at home, at work, on the street). Second, wow, I live in Europe and I have never seen 64+ cars queueing at a single station. If I saw 15, I'd be wondering what the hell happened.
	▲	scq 5 hours ago \| parent \| prev [-]
		With EVs, most of your charging should be done at home, with fast charging mostly just existing for trips. I know not everyone can charge at home (especially if you live in an apartment), but the solution to that is pretty straightforward and a lot more convenient compared with trying to scale up fast charging to match petrol stations.