My experience is probably not typical (I move around a lot and rarely go to the same Starbucks more than a few times) but I'm only about 70% sure that any given Starbucks will have a connection at all. So I only go in if it's really convenient or I have no other options. That's to say nothing of the speed or reliability - both of which are typically mediocre to terrible.

If I knew with certainty that every Starbucks had a fast and reliable connection, I'd probably patronize them 50-100% more than I currently do. Hell, I'd be on my way out of this hotel in search of a Starbucks right now if I knew that!