[throwaway2037]

You raise a great point here:

    > since I didn't write the code, in order to understand it I have to read it. But gaining understanding that way takes longer than writing it myself does.

I remember reading Joel Spolsky's blog 25 years ago, and he wrote something like: "It is harder to read code than to write code." I was quite young at that stage in my programming journey, but I remember being simultaneously surprised and relieved -- to know that reading code was so damn hard! I kept thinking if I just worked harder at reading code that eventually it would be as easy as writing code.

[theshrike79]

“Indeed, the ratio of time spent reading versus writing is well over 10 to 1. We are constantly reading old code as part of the effort to write new code. ...[Therefore,] making it easy to read makes it easier to write.” ― Robert C. Martin, Clean Code: A Handbook of Agile Software Craftsmanship

Also:

Everyone knows that debugging is twice as hard as writing a program in the first place. So if you're as clever as you can be when you write it, how will you ever debug it?

— Brian Kernighan: The Elements of Programming Style, 2nd edition, chapter 2

In summary: write simple code, it's easy to read and understand - by future you who forgot why you did something and others.

[Lapsa]

that idea is somewhat true - if you work harder, reading code definitely becomes easier