There is a heavy emphasis on testing the code as the way to provide guarantees that it works. While this is a helpful tool, I often find that the best engineers are ones who take a more first principles approach to the code and can reason about why the solution is comprehensive (covers all edge cases) and clean (easy for humans and LLMs to build on).

It often takes discipline to think and completely map out solutions before you build. This is where experience and knowing common patterns can also help.

When you have the experience of having manually written or read a lot of code it helps at the very least quickly understand what the LLMs are writing and reason about it later even if not at the beginning.