This is the "Happy path" workflow, where the API is designed before any work begins on development of the API or the architecture that will consume the APIs.
It is a logical extension of the "Mobile-First" principle. Because the API design and documentation is generated before any development begins, this means that both the API and API-consuming architectures can potentially begin at the same time.
Some of the process steps are not part of the remit of OpenApiStudio, in fact, OpenApiStudio won't be used until steps 3.4 (or 4) through to 5. However, OpenApiStudio allows to you to import the OpenAPI documents, and it will then automatically generate resource stubs and store the necessary documentation for them.
Each OpenAPI document should only relate to an application and its resources, i.e. create separate OpenApi documents for each account/application and its resources.
It allows you to upload end edit the existing documentation, and will continuously update the internally stored documentation and generate stubs for any resources that do not exist yet.