Evidently I need to get the book you are working from.
I get the circuitous route the oil goes to get to the rockers, but its essentially a constant flow system. Once the system has pressure there is flow through the system until some engineering problem crops up and the system can't overcome that.
That long route to the rockers is one reason why I don't like hot idle oil pressure to get below about 40 pounds. And the engineering of the system screams for a bit more oil pressure.
I've done dyno testing where a reduction of oil pressure was a loss of HP and all of it was at the rockers.
I need to read the book you are. I want to see what the book says. I understand what you are trying to gain. I even did an external feed to the rockers and until I corrected the oil timing to the rods, I kept killing bearings. Then I undid the the external feed to the rockers because it was a bit of a PITA and didn't have bearing or rocker issues.