No idea, but there are certain semi-discrete barriers that I've noticed: 0.8: difficulty with fundamentals. There are people out there who just can't get code

No idea, but there are certain semi-discrete barriers that I've noticed: 0.8: difficulty with fundamentals. There are people out there who just can't get code to compile, or struggle with core concepts like pointers and recursion. 1.2: corporate work frontier. Large "commodity programmer" teams tend to focus more on creating a home (slight, reliable, adder status) for a large number of mediocre players than on developing talent. Most jobs won't take you far beyond 1.1-1.2; even the team leads in most corporate shops tend to be only 1.3-1.4. 1.8: escalating difficulty of getting appropriate projects. You can get to 1.5, 1.6 through side projects, book reading, and exploration in your spare hours. It's quite rare, however, that people get to 2.0 without having the (very uncommon) opportunity to do 2.0+ level work full-time. To push beyond 1.8, you need to get more autonomy in your job than most programmers ever have.