Of course, problems come to light, but absence of problems somehow does not. So spending a bit more time ensuring absence of more problems is not self-evident activity to the manager.

However, it is usually easy to distinguish slow coder from good coder, which goes slowly. If codebase is started and remains healthy, speed of development does not suffer.

With technical debt ridden code speed of development becomes slower over time, and no rock stars can help unless they jut rewrite it...