Modularize later
A principle from The Innovator's Dilemma. An innovation always starts out integrated, and is modularized later.
Source: https://gordonbrander.com/pattern/modularize-later/
Here "innovation" means a new product or service. The principle is that when you are creating something new, you should not worry about modularity ( at least not too much ). You should focus on creating a working product. Once the product is working, you can then think about how to make it modular.
I understand this principle triggers some people, because it is the opposite of what we are taught in school and what we learn in the industry, I also understand this principle can be used as an excuse to "wing it" and not care about the code quality. But I think it is a good principle to keep in mind when you are starting a new project, because the harsh truth is that most of the time, you don't know what you are doing. You don't know what the final product will look like, you don't know what the users will want, and you don't know what the best way to implement it is.