At one of my employers we had a very large and highly skilled dev community and being quant-biased, we tracked code checkins over time, number of tests written, number of pushes to production etc. I was very proud to be about number 3 or 4 out of about 1000 devs on these productivity metrics consistently over a period of 8 years there.
There was one guy however who literally dominated. Not only was he number 1 on any metric, but he did more checkins than the number 2, 3 and 4 devs combined. He had so many checkins that eventually our glimpse code search index whitelisted his userid because it thought it was a keyword in the language.
And it wasn't that he was a cowboy, he was obsessive about code quality, fixing bugs etc and also was top if you looked at test coverage etc. He was just a flat out machine - every day he would just come in and code all day whereas I have spurts of productivity with downtime etc. He didn't seem to need to be intellectually fascinated by a project and was just as productive at the beginning as at the end of a project - one of my colleagues joked that this guy's interest level in any project was always 83% ("Almost but not quite very interested") no matter what it was. He was very skilled and just churned out massive amounts of code all day every day. He never fell into the classic engineer's trap of overcomplicating things - in fact a lot of what he wrote was very simple when you looked at it (and I think that's part of what made him so good - he had a brilliance for finding really obvious, simple ways of solving hard problems) and because he wrote tests for everything he didn't really need to go back and or refactor things much.