Software Design Patterns
As you get better as a software developer you come to realize the importance of software design patterns and that it could help to solve some of the problems you had in your prior experiences, like when your coding something and you find out that the code is getting very messy, especially in large projects when your teammates start developing their own coding patterns and then everyone has their own different coding pattern, and then over time nothing makes sense in the code anymore.
I have seen the codebases of some Nigerians and to be honest, its crap. i don't even know where to start coding because everything is just messed up, no comments, lack of proper indentation, basically zero file structure and then there are weird naming schemes like Controller, coordinator, manager, handler all sorts of different things and no one really has any idea how the code looks like anymore there's data flow going all over the place, if you were to draw the data flow communication graph you might find its basically spaghetti code there would be dependencies all over the place basically, its shit.
This is where software design patterns come in, there are many design patterns but i will brief you on what i think everyone should know. First of all you should think of the concept of simplicity and one way data flow, basically limit the types of objects you have on your system so you might have like controllers, views and data objects and that would be it and if you find that your starting to introduce a bunch of different types like managers, coordinators it'll be hard to understand what's going on there. There is also a software design principle known as Single Responsibility where every class or every method has a single job and it doesn't do more than that and that makes it very easy and quick to reason about what each portion of the code is doing.
I don't really want to take much of your time because this topic is very broad, but let me know if you want an extension of it and if there is anything you dont understand reach out to me at archekit@gmail.com for clarification.