The length was the structure, not the work
The first thing to establish was that the two-month cycle was not caused by the billing work itself. The actual effort of preparing and approving a bill is small; the months came from the structure around it. Approvals ran in series when they did not need to. Ownership was unclear, so work waited in queues nobody was watching. And errors surfaced far downstream, triggering rework that sent items back through steps they had already passed. A long cycle is almost always a structural artefact of this kind rather than a sign of heavy work. Naming that correctly mattered, because it pointed the fix at the sequence and the ownership rather than at the people doing the billing.