> if you can't measure it, how can you meaningfully improve?
The idea that you must have a quantitative measure to improve something is a bit overboard. Process analysis can teach you a lot about how you (or others) work, what the character of that work is, and suggest ways to improve it. For example, Kim's Screenflow session captures can be viewed as a kind of Contextual Interview[1] ... with himself! In that light, the primary goal could be viewed as one of discovery: "how do I work?" versus "how do I improve metric X in my work?" The initial Kata review may suggest metrics for improvement, but it's the continual process of open-minded review that will identify and suggest areas for improvement.
That said, Chong Kim does cite a key metric: time. So on that point, he's looking to optimize his efficiency with the tools. There's a lot to be said for just time efficiency; improving this can be a very liberating experience as a coder. Speaking from experience with contextual interviews done for others, it's often possible to significantly improve workflow by just hitting the proverbial low hanging fruit.
That said, time isn't the be-all, end-all IMO. In the Katas, I'll argue for time as a model which provides structure to that more important inquiry I cited above: what is his working process and learning process for each new problem domain? How can those be improved?
