Almost every coffee shop you visit has a distinct espresso recipe (or many) and a preferred brew ratio. I will link to an article from La Marzocco below that does a great job of describing different brew ratios around the world. There has been a lot of debate over the best way to brew espresso and there are some strong opinions out there on brew ratios. There are so many small factors that go into a shot of espresso and I don't want to spend too much time on that debate. I will say though that there's a huge push in United States for coffee shops to pull 1:1 or 1:2 brew ratios. Everywhere you turn online, on YouTube, and in news articles there is advice on how to pull a ristretto. The interesting thing to me is that most of this advice and information is coming mainly from the third wave coffee movement. Third wave coffee shops represent about 3% of the coffee market in the U.S. - that's it. So, a small percentage of people in the coffee industry are influencing and trying to re-educate people on what the perfect brew ratio is. However, the mass majority of cafes and coffee shops in the U.S. most likely use something closer to a traditional Italian brew ration of 1:3. In my opinion, and this just applies to me, most espresso shots that I've had that subscribe to a 1:1 or a 1:2 ratio (no matter what the origin and roast), tend to be under extracted and very sour. Maybe that's at the hands of an inexperienced barista, but it seems to me that sour and under extracted are currently in vogue. -Van