GPT-3 Fine-tune Completion Length

Has anyone figured out the optimal completion length for fine-tunes using the open-ended method? (no prompt, just completions). Should we prefer to have large paragraphs or should we try to split our content up into a few sentences for each completion?

Im trying to figure this out myself too.I did find this post so it seems we should split them and chain them as Prompt / Competition then Prompt / Completion? Does that work?