Is there a practice of purposefully going with very loose TDD workflow? [migrated]

Does TDD always mean to constantly add implementation inside Test-Develop loop? I saw once an efficient developer, who prototyped a part of big web app in Python. He did a few things in a day or two - wrote multiple broken/empty tests at once, as a way to describe system use cases - wrote only mocks and interfaces (abstract classes) for the code that might go into the above sketchy tests - wrote a few thin implementations inside rare the tests, in order to demo how interfaces and top-down api calls are connected

That look quick, and efficient to me. That gave a good understanding of how the design works and I believe that looked like a controllable experiment for him.

While I myself follow the TDD very standardly - add test/ add code/ add more asserts into test. I almost immediately jump into development of some function body. Is there a word/name for this efficient and broad development in TDD? Does it look more like a personal experience - or it's the part of TDD that I've somehow missed and practice it very literally instead of doing "smart code sketches"?