I worked with a developer briefly who would produce code at an extremely high speed (this was before LLMs) and I've observed them write 50% of the code for two projects in the matter of a few days.
While I never got around to asking them how they coded so fast, this was probably one of the tools in their arsenal.
I can imagine it's practice and self-disciplilne; pick and know a language/tool instead of reinventing the wheel or doing research first, write like you've always written, do new projects in that same toolkit multiple times, and (self discipline), just get on with it.
I struggle with that tbh, every time I'm on a new project I get into a "beginner's mindset" and look up the basics for a tool again instead of trusting myself that I know enough and what I write will be good enough.
FYI in case you didn't read the article - it's not about LLM coding but about a blind software developer who uses a screenreader at 800wpm to read code. It's really astounding to hear how fast that is I recommend checking it out!
I understand it's about LLM coding, but if I don't put that disclaimer there'll be tons of comments telling me how programming skills are obsolete in the LLM age.
While I never got around to asking them how they coded so fast, this was probably one of the tools in their arsenal.