I've been doing the same thing with Claude Sonnet. A chef prompt keyed in on my activity levels and a separate trainer prompt for workout results. Very helpful but I've never had human pros for those jobs to compare.
Discussion
If you already know what you’re doing human coaches are mostly accountability partners and they mostly shed light on your blind spots which conversational LLMs are even better at because they are literally 24/7 available.
Speed is a feature