I'm fine with a 1k-line function if you just have that many things to do in a row without taking a breath. Breaking it up into smaller functions feels neater when you write it, but when I read it I'm essentially just macro-expanding it in my brain into the original 1k linear version, and that has some cognitive overhead (especially when they end up misordered in the file, or split across different files).

I also have to think about whether there are any other areas of the code that might be calling your helpers, and whether they might break if I change the helper. Seeing everything inlined makes it absolutely clear from local reading that modifying the code only affects the local functionality.

I'm not saying go insane and copy/paste the same thing multiple times, just that 1k-line functions are sometimes the least of all evils. I liked what John Carmack had to say on this topic: http://number-none.com/blow/john_carmack_on_inlined_code.htm...

Another point from that post that I try to take to heart: if it can be a pure function, it should be a pure function (even in C). Bob Martin's style is the opposite.