Racefab57..... IMHO it's not the idea of passing to much water thru the engine/heads. Just having water flowing thru something doesn't necessarily mean it absorbing lots of heat.
Air, water, even your hands can't absorb anything very well unless it's touching it. Only the outside edges of coolant are in contact with the hot passage walls. The center of the column of water are still cool so we use pressure to force the liquid thru the system. This causes it to tumble/swirl so the inner cooler part can contact the passage walls also. Just think of intake ports. They have this boundry layer that's touching the walls... the rest isn't.
Same goes for inside your radiator. It must tumble/swirl around so ALL of the coolant has time to touch the fins & get rid of its heat, otherwise it comes out still warm/hot.