We are essentially talking about situations where variables are partly independent, and here you are trying to bring everything back to a zero sum game already. I shouldn’t be responding at all, but ok, I’ll bite.

Skill.

Writing slow, unmaintainable code is usually a false economy. But many people just don’t know any better.

Take the refactoring Extract Variable, which is probably the simplest example. You name an intermediate value, thereby documenting it. Then hoist it out of the loop, making it faster, shorter, and clear that this value should not change.