Ideal world seldom plays out in reality world. In an ideal world, every person on a team can carry out any task; that way, people can simply swarm to the highest priority item until it is completed and then move onto the next one. In the real world, people are specialized. They have specialized training and experience. They work in unique contexts. They do not have effective skills in every technology from JSF to SQL. In the ideal world, people should only be focused on a single task within a single project or feature.