Henry Ford once sued a reporter for slander, said reporter having said Ford was stupid or words to that effect. At the trial the reporters lawyer got Ford on the stand and began asking him all sorts of esoteric questions. To each question, Henry replied, "I don't know".
Finally the lawyer in triumph said, "You don't appear to know very much about anything, do you Mr. Ford?"
Replied Henry," I do know that with five minutes on the telephone, I can hire men who can answer every one of your questions."
The point is that the President doesn't HAVE to have all this knowledge at his fingertips. That's what staff is for.
To handle the little details.

troll