Might disagree with the author on what is deliberate practice. I would say the implementing code at work is not deliberate practice in the sense that it’s defined in the original 10k hours thesis.

I think in the strictest sense deliberate practice is picking something that you’re weaker at, and spending time deliberately working on that.

I imagine that some part of the author’s 10k hours was working on projects outside their comfort zone, while others were within it. The argument would be doing stuff that you’re comfortable with or don’t have to think too hard about would not be deliberate practice.