The mechanism of the switch is designed so that it rotates the cylinder by one position with each click.
However, Siegman and the many members of the 'Darkhouse' group only know that pressing the switch will move the bullet's position forward by only one position.
In the fourth round, Rocket once again analyzed the revolver to fully understand how the switch works.
After winning the round, he cleverly placed the revolver in front of him and, with complete concentration, observed what was happening in the revolver when he was pressing the switch.
In the final round, from the moment Siegman took the revolver from the box, Rocket observed Siegman carefully without blinking.
Rocket noticed that Siegman only pressed the switch once, leading him to think that Siegman might not fully understand how to use the switch, or perhaps he believed Rocket's success in the third round was merely luck.