When Scaffolds Stop Helping: Evidence Maturity, Orchestration, and Bottleneck Migration in Long-Form LLM Synthesis

This preprint studies external multi-stage scaffolding as a conditional treatment in long-form evidence-grounded LLM synthesis. A five-case 2 x 2 pilot crosses old versus enriched deterministic evidence with one-shot versus a frozen multi-stage workflow under the same model. One-shot generation outscored the multi-stage route in all matched-evidence comparisons. The paper distinguishes evidence maturity from evidence volume and develops a bottleneck-migration interpretation in which the limiting factor can move from evidence availability to model-facing semantics and then to materiality selection.