Allocating the thinking budget

As soon as you build something, the question is no longer "which is best" but "how much thinking, for which step".

Three quantities that move together

Cost rises roughly linearly with reasoning tokens. Latency too: thirty seconds of waiting is acceptable for an analysis, but a deal-breaker in a conversational interface. Quality, meanwhile, follows a curve that flattens out.

The useful operating point therefore sits well before the maximum, almost always.

Route rather than choose

The architecture that works in production doesn't use one model but two or three. A first step, fast and cheap, classifies the request: simple, or multi-step. Simple ones go to the fast model, the others to the thoughtful one.

On real traffic, the vast majority of requests are simple. Routing divides the bill by a significant factor without degrading what matters, because you only degrade what didn't need better.

Where to place reasoning in a pipeline

Not everywhere. In an extraction → decision → writing pipeline, only the decision needs it. Extracting and writing are straightforward tasks.

The common mistake is putting the most capable model on every step "to be safe". You pay ten times over for zero gain on eight steps out of ten.

Measure before you decide

Put together thirty representative cases with their expected answers. Run them through each configuration. You get a quality / cost / latency table on your cases, which no public benchmark will give you.