Step 1 : Introduction to the question "2. If someone is described as "Going twenty to the dozen" what are they doing?"
...1. Having a scratch 2. Trying to add up 3. Doing something quickly 4. Having a beer drinking competition This means that a person is, or several people are, working very quickly at completing something. We don't get to see this happen here very often. It can also be applied more generally to anything that is moving quickly, such as a car going too fast perhaps.