When programming is hard

There are no coding rules.
It's a code that many people see, but there is no response 
even if you shout coding rules, and the code is getting harder and harder to see.
The result is that I am the only one who is sensitive.

Copy the repeated logic.
The code will have the same logic A, A', A'', A'''. 
You can fix the problem quickly, but it's hard later.
Later, there was a problem with A, so I fixed it, and after a while, I am fixing A'... After a while...
Let's subtract with a function what we think is repeated.

Programming languages also change.
C++ 20 years ago is different from C++ now.
Most, but not all, newer versions will find an easier way.
When you ctrl-c ctrl-v on old code, see if it can be improved.

Refactoring
"It's working fine. Leave it as it is."
If I change it, it's my responsibility... I can't touch it