Small pieces are easier to understand. Small pieces can be understood. You can fit the whole thing in your head when it’s a small piece.
If you build something complex from small pieces and then you need to make a change, there’s a good chance you’ll really only need to change one small piece. And if you need to change more than one, you might have identified a new concern, something that might be better as its own small piece.
When small pieces break, they tend to break in a self-contained way. When they don’t work how we expect, it’s usually pretty easy to see what the problem is.
