What I've observed over the 10 years since I got serious about coffee is not so much a series of changing standards, fads and trends, but an evolution in the cultivation, sourcing, roasting and preparation of specialty coffee.

Jim implied an aspect of this evolution when he described the shift from medium-dark to light espresso roasts. As he said, 10 years ago baristas were cramming as much coffee as they could into triple baskets and pulling Ristretto shots. Why? Because if you pulled a classic 14g Normale in 25 seconds those dark roasts would over-extract and you'd get bitter roasty flavors. The overdosing and short pulls were designed to reduce the level of extraction so that, maybe, you'd get some origin flavors like fruit and chocolate instead of turpentine and soot. Titan conicals became the rage during this period because, IMHO, their grind distribution reduces the extraction level of darker roasts.

Another theory of mine (and probably others) is that the overdosed Risretto period came about because U.S. specialty roasters were using 100% Arabica beans for their espresso roasts, and were missing the moderating effect of Robusta beans blended with Arabica beans in Italian espresso roasts.

Alas, there was nothing U.S. baristas could do to completely eliminate the roasty notes . At best, we got hints of the origin flavors that might be there. Thus began the macro trend towards lighter roasts. And with lighter roasts we had to reduce the dose, grind finer and pull longer to avoid under-extraction -- e.g., lemon juice. As the roasts have gotten lighter, it's become harder and harder to extract them. Enter pressure and flow profiling. Pressure profiling extends contact time to increase extraction, while flow profiling uses long, slow preinfusion to "relax" the puck so you can grind finer and achieve very long pull times without choking the machine. Massive flat burr grinder have become the rage because they appear to eek out a tad more extraction from light roasts than big conicals (though I hasten to add that this is based primarily on anecdotal observation not scientific evidence.) And lever machines are back in vogue because they can achieve pressure and flow profiles that may extract light roasts better than shots pulled with pump machines with fixed profiles.

I don't see the increased focus on dose/beverage weight and brew ratios as a fad, either. I think that may have evolved from recognition that consistency is the holy grail of espresso -- without it you simply can't dial in properly -- and eyeballing doses and volumes doesn't produce consistent shots. Also, I believe Andy Schecter's seminal post on brew ratios here on HB had considerable influence on understanding the properties of different brew ratios, which in turn highlighted the importance of accurate dose and beverage weights. Finally, I think the emergence of affordable, easy-to-use refractometers and accompanying software further pushed the emphasis on using scales to achieve accurate dose and beverage weights for a desired brew ratio.

[To avoid inciting an argument, I must add that using a scale to weigh dose and beverage, and/or using a refractometer to measure strength and extraction, aren't substitutes for using your eyes, nose and tongue when dialing in a shot. Measurements can provide useful information, but you still have to assess the flow rate and color, and of course smell and taste the shot.]

My guess on tamping is that the evolution of the technique (lighter tamping, no tamping, use of grooming tools instead of tampers, etc.) is a function of the huge growth in the number of cafes and restaurants offering espresso, as well as the number of home baristas. As more people pull shots, more experiments are conducted and we get more information about what works and what doesn't. Further, there are a lot more espresso accessories on the market to try than there were 10 years ago.