Single models versus model routing: correct dispatch still needs quality checks
Compare one-model serving with rule-based dispatch, checking selection, fallback and evaluation samples for maintainable services.
Choose an approach
Keep a simple baseline when one model meets important tasks. Consider routing when different models have verified strengths for distinct needs. Rules or extra classification add dispatch and fallback maintenance. Successful routing does not establish answer quality; inspect selection and results separately rather than inferring savings from unit prices.
Task selection differs from balancing equivalent deployments
LiteLLM Router distributes deployments and handles fallbacks; OpenAI recommends task-based quality and cost assessment. Balancing equivalent endpoints differs from choosing models by task difficulty. The latter needs categories and quality thresholds; short inputs are not necessarily easy. Define the routing decision and retain selected models and rule versions to explain output changes.
Check misrouting and outcomes on the same task set
Use varied tasks and boundary cases, establish one-model results and then record actual routing choices. Separate misclassification from answer errors and test unavailable models. Fallback outputs still need the same quality threshold rather than merely returning text. Count classification and retries in total consumption. No router or model comparison was run and no combination is claimed superior.
Recheck rules and capability boundaries after model updates
More models increase interface, parameter and version maintenance and may invalidate rules. Keep a one-model fallback configuration, change explainable pieces incrementally and replay failures. Retain uniform handling where task quality cannot be classified reliably. Include diagnosis of routing errors alongside final-model prices. Adopt only when calls and fallbacks are traceable and complexity yields observed benefit.
Checked sources
These sources support the concepts and methods described here. Examples and test scope are labeled separately; check the version of the tools you use.