How often do you deliberately read code?

I am currently reading the book 97 Things Every Programmer Should Know and I come across again to the most obvious but less followed advice ever.

You should read more code!

I like reading technical books and this is not the first time I see this advice.

Are you deliberately reading other people code?

I personally read snippets of code in books, in online videos and of course I read and review code written by my colleagues at work.

Is it enough?

I don't think so.

Code in books or online courses are just snippets so they can helps you to learn a specific technology or best practise but they do not help in teaching you how to read an entire code base or quickly jump into a new project.

Code at work is surely a source of learning but often you just read the code related to the task at hand instead of learning the overall project.

Programmers are writers. 

Great writers read books. 

Great programmers read code.

To make things harder, there are no books on the market teaching you how to read code, how to learn a code base from scratch and be productive quickly. This is a question I asked often and I rarely found an answer. 

Why some people are so good in jumping in on a new project?

They surely know the language and the technologies but more importantly they are used to read code, they can read and understand code quickly!

This is something you need to learn by doing.

There is no alternative.