If you mostly use chat AI and just saw the GPT-5.6 launch post, the easy mistake is thinking you need a longer prompt now. Prompt bloat is eating GPT-5.6. [C002] Before upgrading, delete half the old prompt.
The launch line sounds huge: "GPT-5.6: Frontier intelligence that scales with your ambition." [C001] My takeaway is smaller. Let the task scale first, not the wall of instructions.
Why this matters to normal chat users: if you only follow the hype, you can waste time, money, and attention in the wrong direction. A model update is worth watching only if it changes your next decision, not because the feature list looks long.
The docs-based point is simple: start with the smallest set of instructions and the fewest extra tools. Long prompt blocks, old context, and repeated rules can slow replies, raise cost, and make the model wander or repeat work.
One detail flips the usual advice. GPT-5.6 is more sensitive to lines like "Be concise" or "Keep it short." Shorter can mean missing steps, not better work. That warning comes from the docs, not from one private app test.
So this is not "prompts don't matter." It is: keep the task clear, keep a few hard rules, and delete half the legacy prompt before you upgrade. Then compare outputs. Share this with the person who still thinks every better model needs a longer prompt.