The key thing to remember when thinking about IT architecture is that it is a tool independent philosophy. The goal of architecture isn’t to tell people how to employ the technology, but to give direction as to how to guide that process. Meaning… it doesn’t follow the project management level tools such as waterfall or Agile which define timelines, delivery dates or any specifics to the deliverables. IT architecture focuses more on setting common vernacular and standards so that disparate teams working on larger projects have a clear understanding of the goals, expectations, assignees, exit criteria, et al.
The goal of IT architecture is to help define clear communications between various development/delivery teams, their key stakeholders and business executives to ensure a successful implementation of any project or component.