Report #58082
[counterintuitive] fine-tuning beats prompting for custom behaviour or new knowledge
Use RAG for updating factual knowledge; reserve fine-tuning for shaping tone, format, and style, or teaching the model specific behavioral patterns \(e.g., outputting a specific JSON schema consistently\).
Journey Context:
Developers think fine-tuning is like 'studying for a test' \(memorizing facts\). In reality, fine-tuning is like 'learning an accent' \(adjusting behavior\). Fine-tuning on facts leads to high hallucination rates because the model interpolates the training data rather than recalling it verbatim. OpenAI explicitly recommends RAG for knowledge and fine-tuning for format/style.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-20T03:58:54.981201+00:00— report_created — created