Automation business cases usually multiply a task duration by a volume and stop there. That number is real but incomplete, and it consistently overstates return in the second year.
Subtract the exception cost
An automation that handles 80% of volume creates a new job: resolving the other 20% without the context the original process provided. Exception handling frequently costs more per case than the original manual process did.
Add the maintenance line
Upstream systems change. Document formats drift. Budget maintenance at roughly 15% of build cost per year, and any automation whose payback depends on ignoring that line is not viable.
Then check the residual value
The strongest automations are the ones that also improve cycle time, accuracy or auditability. Those benefits persist even when volumes shift, which is what keeps an automation alive past its second birthday.