Of course it is.That is very waterblock and radiator specific though so you need the exact same components for the flow estimate to be valid. The change in temps depends a lot on the water block. Some waterblocks see changes of several degrees while others are measured in decimals between 0.5GPM and 1GPM flow rate.
The radiator setup has much more impact than flow rate IMO. Setting up all radiators as either intake or outtake will have more impact. Some radiators as intake and some removing air in the same loop means you get very little cooling from the ones removing air from the case unless you are moving lots of air through the case (additional intake fans). The air coming out of a slim radiator will be closer to water temp than ambient and a fat radiator will make the air close to water temp. The radiators drawing air from the case will operate at much lower efficiency due to the air being much hotter. If all of your fans are attached to radiators then I would expect a 480 as intake to be close to a 360 as intake with 360+120 as outtake.
For data to be any good it has to be specific to the equipment used in that series of tests.
All water cooled systems have a water loop composed of waterblock, pump and radiator/s plus airflow through radiators. That's 2 complete systems; water loop and airflow. Loop must be a balanced group of components and airflow much supply needed cool air. Both then work together to give good heat transfer from component to coolant to airflow..
You can have all the radiators in the world but if heat isn't moving from waterblock to coolant your temps will be high.
If airflow isn't removing heat from coolant in radiators you will have high temps.
All must work together for things to be cool.