I don't think any such benchmark should exist. As long as the function only does one thing there is no upper limit. Artificially splitting a large function only reduces readsbility. What would you name the parts? do_stuff1(), do_stuff2(), do_stuff3()?

I have seen very clean codebases with a handful very long functions, but they were no issue she nice they only did one thing.

I personally write quite short functions but I have never understood why people take issue with large functions. Those are one of the easiest things to fix in a bad codebase. It is much harder to clean up after someone who used too small functions.

A smaller chunk that no one else calls should just be included. The break up is actually hurting undertsanding and maintainability.

Except the only real rule is that rules are wrong.

All there are is different and actually contradictory pressures for different and actually contradictory priorities that are all true and valid at the same time even though many contrdict. The correct thing in each given moment is whatever makes the shortest rubber band lines between all priorities.

Sometimes that will be a very large single function even if some other times that will be a bunch of 10 liners.

And that's why my monitor is 2560x2880.