I think the longest we've spent at a Supercharger was maybe 20 mins. The charge rates really drop (like charging any battery), so it often makes more sense to just stop a couple times with a low battery and add another 100 miles of range in < 5-10 mins.

But I would hope that Tesla has much better data on their users to be able to determine how long people would stop, and where.

I would assume a better model might be locating the supercharger near a robust/successful location with plenty of restaurants and coffee shops.

but some superchargers are in pretty desolate areas - that might be a better place for "the company cafeteria"