> The idea is that automated ranking tools used by recruiters/HR are ultimately use the very same LLM, so you are improving your ranking assigned to your resume by those ranking systems.

Working in HR-tech, that is definitely happening, and "self-bias" is a thing with LLMs so if you can guess what the employer/screening-process is using then that's a bonus.

That said, we should distinguish between "Hey robot tell me if X matches Y" prompts, versus model-weights comparison. In the second case, the system feeds your resume into a model with no prompt, grabs all the magic math numbers, and statistically compares them to the magic-numbers if the model had been given some "ideal" resumes.