Careful -- in these studies the subjects are writing tests before writing code. In practice there are 'test-heavy' devs who use factory data and the test suite

Careful -- in these studies the subjects are writing tests before writing code. In practice there are 'test-heavy' devs who use factory data and the test suite to run skeleton code with crashpoints, and switch actively between test and imp files. This has tests & implementation being written in parallel vs strict TDD which has us finishing tests before writing program logic. Most test suites depend not just on functional requirements but also on implementation details, so it seems obvious that tests-before-logic development is inefficient.