Asked about The levers, in order
When is model routing a bad idea?
An answer that works
When you cannot measure which requests are hard, or when a failure is expensive. Routing adds a decision that can be wrong, so it needs an eval showing quality holds and a fallback path when the small model is not confident.
Reading an answer is not being able to give one. The section that teaches this is The levers, in order, 3 hours of Cost & latency engineering.
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