Reimplementing stuff from scratch, overengineering and, if you’re coding in a compiled language, knowing a bit of assembly to be able to make better performance-related decisions.
EDIT to clarify the overengineering part: the idea is not to do it at work obviously because there you will have to meet deadlines and you will have to spend time on what’s most important, but the idea instead is to do that when working on your own personal projects. Try to make every component of your project as “perfect” as possible as if you were trying to rebuild a Mercedes-AMG car. That’s how you’ll learn a bunch of new tricks.
Reimplementing stuff from scratch, overengineering and, if you’re coding in a compiled language, knowing a bit of assembly to be able to make better performance-related decisions.
EDIT to clarify the overengineering part: the idea is not to do it at work obviously because there you will have to meet deadlines and you will have to spend time on what’s most important, but the idea instead is to do that when working on your own personal projects. Try to make every component of your project as “perfect” as possible as if you were trying to rebuild a Mercedes-AMG car. That’s how you’ll learn a bunch of new tricks.