Oil system myths

Correct, but pressure rises with RPM on a positive displacement pump. The bypass does close once the pressure drops, but so long as the pump is spinning fast enough to produce more pressure than the bypass is set for, the bypass will remain open. The further rpm/pressure increases after hitting the bypass stage, the more oil will flow through the bypass.
.
Another thing to consider is the thickness of the oil and the temperature.
There comes a point in time where you might want to put a higher pressure bypass spring in the pump also.
But until you enlarge the suction side of the pump it won't make much difference.