Not sure I totally agree, but one strong point against factoring in-line code out into a function: You have to understand everything that calls that function b

Not sure I totally agree, but one strong point against factoring in-line code out into a function: You have to understand everything that calls that function before you change it. This is not always obvious. It takes time to figure out where it's called. IDEs make this easier but not bullet proof. Getting it wrong can cause major, unexpected problems.