Robert Martin's "Clean Code" is an incredibly useful book which helps write code that Fits In Your Head

It has the exact opposite effect. It leads to code that doesn’t fit in your head.

Because his style of coding leads to code where everything useful are 10 levels deep in nested method calls. If I want to understand how the code works and how my changes will affect the overall picture, I need to keep a dozen methods in my head and how all of these are connected to each other.

And he’s mostly working with global states, so knowing where variables are assigned is just a huge pain.

So many times I’ve looked into code like this where I finally find what I’m looking for, only to forget how I even reached this part of the code. So I need to backtrack to remember how I got there, but then I forget where that damn thing I was looking for is. And I go back and forth until I figure out a mental model of the code. It’s awful!

Compare that with just having one big method. Everything is in front of me. I don’t need to keep that many things in my head at the same time, because everything I need is right there in front of my eyes.

Sure, sometimes breaking out to separate methods can make it easier to communicate what the code does and the boundaries of each scope, but if it’s overdone it leads to code that’s impossible to work with.