My understanding is that “10,000 hours” isn’t a strategy, or rule, or evidence-based observation but rather a catch phrase of Malcolm Gladwell’s to make memorable a finding that he references in his book Outliers. The finding is by Anders Ericsson, it’s detailed in his book The Path To Excellence, along with his evidence, and it says that extensive Deliberate Practice is what makes an outstanding expert, and that instead people generally mistakenly assume that semi-automatic repetition strongly correlates with expertise development, which it does not.

So counting how many hours you’ve been working in a field is the exact mistake that most people make. Gladwell’s book has reinforced that confusion.