Top-Tier Model For Everything (Cost)
Anti-pattern: route every request through the highest-tier model regardless of difficulty, treating cost as a model-choice problem instead of a routing one.
Problem
Cost grows 5–20× compared to a tiered system, with no measurable quality benefit on the easy 80–90% of traffic. The team only notices when the bill arrives. Rationalizations like 'quality matters' or 'simpler to have one model' justify it post-hoc. When budget pressure forces a fix, the team has no telemetry on per-request difficulty and cannot route safely.
Solution
Build a routing layer that classifies each request by difficulty (heuristic, classifier, or fast model judgement) and routes to the smallest model that handles its class well. Reserve the top tier for requests escalated by low confidence, high stakes, or explicit user choice. Pair with complexity-based-routing and multi-model-routing. Track cost-per-request as a first-class metric.
When to use
- Never as a steady-state design. Cite when reviewing model defaults.
- Add a difficulty router and reserve the top tier for the hard minority.
- Track cost-per-request as a first-class metric.
Open the full interactive page →
Diagram, neighbourhood map, code examples, related patterns and full provenance.