There is a point when you've over-explained your point.  
You've said more than what needed to be said.
You've justified, advocated, and defended enough.

What is the over-explanation for? Who is it for? 

The over-explanation is for you - the communicator. And it is for self-assurance.
That you said what needed to be said, covered the point from every angle, and for self-justification.  

I'm trying to find the simplest and most direct way to communicate.
And I am trying to be "okay" that you'll make of it what you will.  

The art is not the words.

It's the response.