Why do troops stand guard, usually for several hours?

A class lasts for two hours, and the army often says several packs. For example, six packs a pack means six people pack a sentry, and no one shifts twice a day. Soldiers should always hold their heads up, chest up and abdomen in. \x0d\ Most of the relevant regulations on standing guard come from the Internal Affairs Regulations of the People's Liberation Army of China \x0d\ Chapter 10 Security \x0d\ Article 158 In order to ensure the safety of commanders, organs, troops, equipment, materials and important military facilities and prevent them from being attacked and destroyed, army commanders must closely organize security work and educate security personnel to be vigilant and earnestly perform their duties. \x0d\ Article 159 When organizing the security service, the commander of an army must: \x0d\ (1) make careful arrangements for the security tasks according to the instructions of the superior, the situation of the station and the nature and quantity of the security targets. Usually, security tasks are assigned to the nearest detachment; If the stations are relatively concentrated, a guard can also be organized. \ x0d \(2) Organize the detachment leader who is responsible for the security task to investigate the terrain on the spot, make clear the position of the post, the security task and the contact signal, and put forward requirements. \ x0d \(3) Regularly check the implementation of security tasks, and handle problems in time when found. \x0d\ Article 160 The detachment undertaking the security task shall earnestly carry out the security professional training and strictly perform the security duties. The head of the detachment shall organize the guard service according to the specified guard tasks and requirements, and make all members of the detachment clear about the following matters: \ x0d \( 1) The nature, characteristics and safety requirements of the guard target. \ x0d \(2) The position of the post and the surrounding terrain and environment. \ x0d \(3) Dispatch sheets of foreman and security guards. \ x0d \(4) Health responsibilities and contact signals. \ x0d \(5) Handling principles and reporting methods of emergencies.