1. Boost morale: Shouting can make gang members feel United and organized, thus improving their morale. This is very important for a criminal gang, because they often have to face the pursuit and pressure of law enforcement departments.

2. Establish authority: Shouting can make the leader or gang leader establish his authority and make other members obey orders. This helps the gang to maintain consistency and efficiency in carrying out criminal activities.

3. Be vigilant: Shouting can remind gang members to be vigilant and pay attention to the surrounding environment and potential risks. This is very important for criminal gangs, because they need to avoid being discovered when committing criminal activities.

4. Strengthen belief: Shouting can sometimes strengthen the belief of gang members and make them believe that their actions are just or profitable. This helps gang members to engage in criminal activities more firmly.

5. Sense of ceremony: Criminal gangs often regard the shouting before starting work as a ceremony, which helps to create a team spirit and an atmosphere of unity. Although this ceremony may be questioned morally, it may be regarded as a means to strengthen team cohesion in criminal gangs.