When I was firing competitively, I dry fired 10 per each live round.
The dry firing was conducted with a pencil with tape around it so that it did not rattle in the barrel. When the hammer fell it launched pencil into a target taped to a wall which was 2 inches in front of the barrel.
The pencil made a mark which allowed us to see exactly what we were doing. If the tape was properly applied we would achieve groups of 1/8 to 1/4 inches. Flyers were obvious.