Very often I advocate the flush-and-go method because I feel like some folks will benefit like I have by exploring the lower end of the temperature curve. To me, it's all part of developing a familiarity with one's machine. I think this is a key (in my own experience) for making more enjoyable espresso at home.
Developing a "feel" for my machine's operating characteristics lets me make temperature adjustments "on the fly" and often without thinking about it very much at all. It starts (for many) after finding bitterness in the cup. I have found (after helping a few people) that many folks do not understand how quickly some HX machines recover and/or how much water needs to be flushed before running the shot.
If my first shots (of a new roast or blend or bean) have an edge then I'll flush more or wait less.
If the shots have any sourness then I may wait more or flush less (or both).
If you really want to accelerate the learning curve for your machine, then take some temperature measurements.
- Measure the temp of the flush itself.
- Measure a "blank" shot pulled immediately after an 8-ounce flush (from idle).
- Measure the water temp 20 seconds after an 8-ounce flush (starting from idle).
- Measure the water temp 40 seconds after an 8-ounce flush (starting from idle).
- Measure the water temp after flushing 8 ounces, then waiting 30 seconds, then running a blank shot then wait a full minute then flush 2 ounces then run the blank shot and (you get the idea)
It's not a prescription. It's a suggestion.
Take a few measurements at different conditions to develop a feel for how your machine behaves and then adjust for taste.
