Do you think Business Process Analysis is usful in revenu assurance activities ?

Yes, it has a very long lasting impact on Revenue Assurance Activities. The scope of Revenue Assurance Activities may range from "Bringing new customers onboard" to "Recovering from bad-debts", but a REAL Business process ANALYSIS can help us understand all the parameters of entire cycle. By understanding each and every atomic level detail, we can assign relevant / right resource / time for each task.

it depends the then market strategy

Using a Business Process driven approach for Revenue Assurance or Revenue Recognition is very useful. In essence Revenue cuts across multiple business process mainly tied to Finance & Accounting through 3 towers Order to Cash, Record to Report and Procure to Pay.With a strong foundation layer of business process it will help organisation realign their business goals through extensive diagnostics for an As-is-To-Be road-map.