Semi-fixed my banjo bolt by tapping the banjo and screwing in a 1/8 NPT brass pipe nipple.
Ran the test.
At idle it was 55s for 1L, ~2min for 2L.
With my wife trying to hold it at 1500-2000 rpm, it was 1L in about 51s, 2L just about 2mins.
Wasn’t going to sit in my driveway slamming my engine at 3000+ rpm to test further. But this link says the pumps for Cummins trucks are rated at 52.8GPH for a 5.9 L engine notionally heavier loaded for longer durations.
https://www.torkteknology.com/technical-article-1-cummins-lift-pump/
They tested 0.59GPM peak flow on the Cummins lift pump.
So I think 1LPM is probably fair based upon their testing and mine indicating that flow is roughly independent of RPM.