What separates a grandmaster from an international master in chess?
It’s his level of positional understanding and ability to formulate an accurate strategy on ANY move, in ANY position, and at ANY time. The process is subtle and subliminal—not much on the outside, rather on the inside.
If you watch a GM commentate on a chess game, it looks as if he is spouting some “common sense” ideas.
BUT… it is not so.