Comment by JonChesterfield

I worked with a guy who could handle loops nested half a dozen deep with data dependencies woven through the structure with exactly the same apparent cognitive overhead as for i = 0, N. The sort of structure you get when you arrange a difficult calculation to match the cache hierarchy of the target machine. Didn't do comments or variable names with much enthusiasm.

He was superb at finding errors at code review. As in looking through code someone else had written and pulling out the mistakes. Presumably everything looked completely trivial to him, regardless of how tangled the control flow had got.

Whitney may be similar.