Requirements
Get requirements right the first time. Create API's that users can try and give feedback, then implement changes based on that feedback in hours/days, not weeks/months.
Running Start
With working API's in your Sandbox, you can use these to jump start testing and user interface development instead of waiting until the final API's are ready.
Documentation
From Sandbox API's, you can generate OpenAPI documents instead of creating docs by hand or even worse, generating from source code.
