[mdaniel]

My mental model is that the system prompt isn't one thing, and that seems even more apparent with line 6 telling the model what today's date is. I have no insider information but system prompts could undergo A/B testing just like any change, to find the optimal one for some population of users

Which is to say you wouldn't want to bake such a thing too deeply into a multi-terabyte bunch of floating points because it makes operating things harder

[reitzensteinm]

OpenAI automatically caches prompt prefixes on the API. Caching an infrequently changing internally controlled system prompt is trivial by comparison.