This is my opinion about the Subaru oil pump, I have no facts to back it up.
The specification say 49.7 US qt per minute. So almost 1 quart per second.
I think that is it's capability.

The actual flow is determined by the pressure, viscosity and the bearing clearances.
If the full flow isn't needed the pressure relief valve allows oil to flow from the high side of the pump back to the low side. I suspect at high RPM's this is always active. The spring at the pump is set at 85 psi. The pressure goes down the further from the pump. like a skinny long garden hose.

I am going with a 2 qt accusump.
I think it might supply oil for 10 seconds.(just a guess)
With 7 quarts of oil in the engine, I can't imagine the bottom of the pan being dry.
Remember, just my opinion.
Bob