Ad-hoc prompting reproduces the drift you are trying to fix
If five people describe the company five ways to a model, they get five voices back — the same fragmentation as before, produced faster.
The fix is not more prompting skill. It is a shared, versioned block of brand context that everyone starts from.
What belongs in the block
Positioning in a sentence. Who it is for and who it is not for. The three proof points. Tone rules expressed as examples. The banned-phrase list. What we never claim.
That is usually under a page, and it is the same material a good voice guide already contains — which is the point. You are not writing new artefacts, you are making the existing ones machine-readable.
Keep a human on the exit
Generation gets faster; accountability does not move. Someone still has to read what goes out and be answerable for it.
The check does not need to be heavy. It needs to exist, and it needs a name attached to it.