Use a quality-constrained cost model. At equal accepted-output service and constant variable costs, a simplified operating break-even is extra fixed monthly cost / per-task variable saving. If the variable saving is zero or negative, that simplified route has no positive break-even volume.
Hypothetical example: the current path costs $0.12 per task with no extra fixed cost; the specialist path costs $0.04 plus $8,000 monthly fixed cost. At equal acceptance and service quality, operating break-even is 100,000 tasks/month. At 200,000 tasks, monthly costs are $24,000 and $16,000, a difference of $8,000. A hypothetical $60,000 initial investment has 7.5 months’ simple payback after launch if that difference persists.
Now halve the baseline variable price to $0.06 as a stress scenario, not a forecast. Break-even becomes 400,000 tasks and the specialist path costs $4,000 more at 200,000 tasks. The business case changes without any change in the specialist model itself.
Real models should account for differing accepted-output rates, non-linear capacity, review, retries, transition overlap and cash timing. Reject candidates that miss mandatory quality rather than treating harm as merely another cheap output.