That's a great question.

Let's assume your engineer is indeed doing great, and you are not involved at all in their day. They plan things themselves, execute, and barely talk to you, all the while succeeding. In this case, the only thing you do is 'not interfere', which is not much. The question should be - how much better can that engineer be, and what can you do to support them? Maybe just helping to choose the right projects, connecting with people inside the company or from your previous companies is enough.

I believe that if you can't point to specific things you did to support that engineer, you didn't do that great of a job.