How do you quantify the 1% per 21 days improvment? There are no easy-to-get-at brain weight scales yet. I agree with your incremental change mindset, I just find it hard to measure.Agreed. 21 days is a good audit point. If you can make the case to yourself that you've improved the total value of your skill set by 1 percent, then proceed normally.
This is equivalent to 19% per year. That's measurable if you pay attention to market trends. Keep in mind that if you stick with one job, you're likely to bank only half of that increment. You probably won't get 20% pay increases unless you work for yourself (in which case your expectancy might go up by 20%, but you have a lot of volatility). You'll get 6 to 10 percent per year. It might still be worth it to stay in the same job, if you feel like you're learning a lot. Part of the reason why the pay improvement is slower is that the best engineers tend to prefer more interesting work (and stability, as they get older) over aggressive salary growth.
Here's a scale for software engineering: http://michaelochurch.wordpress.com/2012/01/26/the-trajector... . Each 0.1 increment seems to be about a 26% increase in abstract business value (or a 10-fold increase per 1.0) and about an 8-15% increase in salary. You should be aiming for 0.1 every 18 months, which is hard but doable, although it usually requires pushing back at work sometimes.
An addition to your proposition that you needs make your decisions in order to improve: You also need to actively learn from your failures. Many people just go like "That sucks, it did not work out" without ever asking the Why. That's not enough to learn, and one could even learn the wrong lesson from a failure.
Absolutely. No disagreement there.