A local maximum will come from those who recently acquired the knowledge. But truly great teachers, that can consistently reach students of diverse aptitudes and thinking styles, are made over the course of decades.

There's a problem that comes up there - anyone on the bleeding edge of a field is full of distracting trivia about edge cases and theories that is simply too much for a beginner to grasp.

If the expert has enough "intellectual empathy" to put themselves in noob shoes then they can still teach well. However, if they can't state without reservation that 1+1=2 then they are no good for beginners.

I used to say "the following statement is a lie, but it's true enough for today." If a (usually advanced) student asked me what that means I'd go into the details, but you need to lay out a solid skeleton before you can start hanging irrelevancies on it.