So then market fit exploration benefits from tracer-bullet, but you might do iterative reimplementation instead. And it might be overkill for a one-shot market test. MVP is largely orthogonal to end-to-end - "Submit button emails founder who does the thing by hand over breakfast" is fine MVP but isn't very end-to-end. And a non-MVP non-product end-to-end can be tracer-bullet or not. A soundly architected low-debt end-to-end yes, a hackathon high-debut "to adjust, rewrite", or a throwaway end-to-end exploratory spike, no.