0 minutes. In order to prepare for an incident, an emergency response guidebook needs to be studied and used before an incident occurs. During a critical incident there is no time to be constantly consulting a guide, but rather should be inherent knowledge that is practiced and reviewed frequently. This may include engaging in discussions, on-going in the job training and role-plays with peer or colleagues. The ERG is a resource to learn from and refer to, but not in times of a critical incident.