If you're an amazing, top 1% software engineer, and you switch jobs to become a penetration tester, you're not going to be top 1% day one. There's knowledge specific to penetration testing you'll need to research and absorb and practice before you're good.

For the models, it's always day one. They don't learn from experience. Whatever they know after training is all they'll ever know. So if you don't teach them penetration testing in training, they won't know it. Maybe they could theoretically derive everything from first principles, and so could a top 1% software engineer, but that's a very slow and inefficient way to do things.