Normal rocket development: First it fails to lift off. Then it crashes on launch. Then it reaches orbit and fails to de-orbit. Then it crashes on landing. Then it works, and works, and works.
Don't be confused by normal engineering progress. This is a hard problem to solve. Each step informs the next step, and it improves by 'stepwise refinement'.
Normal rocket development: First it fails to lift off. Then it crashes on launch. Then it reaches orbit and fails to de-orbit. Then it crashes on landing. Then it works, and works, and works.
Don't be confused by normal engineering progress. This is a hard problem to solve. Each step informs the next step, and it improves by 'stepwise refinement'.