Team members learn from each other about quality and requirements for the deliverable

Everyone in the team can ensure that the deliverables is consistent, in that if everyone does a part of the work,  a structured walk-though will help ensure that team standards are kept across the deliverable

Everyone in the team can understand the complete deliverable, even if each member has only worked on part of it

Everyone in the team can check the work, thus improving the quality of  deliverable