This approach also breaks down for the same reasons the Waterfall model doesn't work. A lot of information is discovered during development, which causes specs to be outdated or wrong. At that point the LLM context is deeply poisoned, whether from the specs themselves, or from the rest of the codebase. You can try to update the specs or ask for major refactors, but that often introduces new issues. And as the context grows, the chances of producing working code diminish significantly. The only way forward at that point is to dive in yourself, reviewing, fixing, and refactoring the traditional way, and wondering whether this workflow has really made you any more productive.