When Andy Gray balances stones to make his beach sculptures, he says he listens to the stones with his hands. I feel I know what he means. He becomes very focussed on the weight of the stone in his hands and how the balance moves and rolls around, until eventually, he finds that magic spot where the stone will balance all on its own.
I see a symmetry with composing images. When I look for compositions, I feel when the composition is just right. A step to far forwards, a slight movement of the tilt of the tripod, a millimetre adjustment, is often all it takes to make something feel right.
Andy Gray's sculptures are the best analogy I can come up with, on how one should know when a composition is right. Your attention to detail and to a gut reaction, are essentially all you need.