Han Sen was no master at rock-paper-scissors, but he had made an effort to improve his ability to make more accurate predictions. It wasn't for games, but for knowing in advance a creature's habits and movements.
For an archer, it was undoubtedly a very important ability.
Almost anyone could shoot at a target. And there were numerous people who could hit the bullseye from 150 feet away. However, creatures wouldn't stand still all the time, so it was important to be able to predict their movements.
To grasp the fleeting opportunity, prejudge the enemy's action, and shoot to kill were Han Sen's specialties. Or he wouldn't have chosen archery to practice.
When he first entered God's Sanctuary, he didn't have a nice bow and arrows, so he practiced sneak attacks, which had even higher demands for one's pre-judgment and reflexes. A little mistake would leave him unable to kill a creature with one blow, which would result in the most terrible counterattack.