Do you have project documentation for teamwork?

Question

Programming

And in what form this documentation and what detailing.
The essence of the issue is that there is a large project (more than 300 thousand lines of code) and a new developer comes to it: he is told that he was washed down with a black list of IP addresses. He makes his own method of checking ip for correctness in the BlackIp class, etc., then he is told no dude, we already have such a check for correctness of ip in the AllCheck class for example. Who has their own ORM in the project, do you write some kind of documentation or examples of basic queries for it?
What level of detail do you need documentation and what would be the correct description in it? Folder structure, classes, who is responsible for what, class methods?
Or do you not care and you never write any documentation so that newcomers do not sit you down?

Answer 1

In large projects, tasks are set through a bug tracker, in which the ticket should contain a desigon solution approved by the architect (or who controls the architecture of the project as a whole).
There should have been an indication of whether a new method needs to be created, or there is a ready-made one written by an experienced employee.
PS Juniors and even mid-laners always need to clarify the task. The senior must guess and clarify how to solve the task.

Answer 2

Commenting is enough to quickly understand the components of the code.