According to project_revenue module:
The project revenue module computes revenue and cost per task and project.
The revenue uses the list price of the product. If the product’s unit of
measure is time based, the revenue is computed as the product of the price and
the hours of effort otherwise the price is considered as fixed.
The cost is computed by summing the cost of all the linked time sheets and the
linked purchase lines.
When combined with the project_invoice module, computing revenue using the effort sounds strange if invoicing based on timesheet is used. Is this an oversight? Otherwise, what is the use of using effort for computing revenue in those cases?