I grenaded my slant 6

The psi is the same, full groove or not.
The leakage is the loss and that's bearing clearance related. ..so if the bearing clearance hasnt changed.. why would a tiny channel down the middle make a difference.

Most of these bearing feed holes are smaller than the ones in the block as well.
I bet you would alter psi opening that bearings feed hole given if the clearance is on the big side already.
The point where idk. I dont run them .003+
Balance in the system.
Are we opening up galley/feed sizes and not the bearings or are we doing both..then you need more oil psi/volume..which ever side you fall on.