I have tried to scientifically test prefilling the filter by using the oil pressure gauge response time
there was zero difference between prefill and not prefill. Dart SHP 9.5 deck SBF block, standard volume pump, 0w50 oil and about 95 deg F air temp if it makes any difference
remember you still have to get the pump to suck up the oil from the pan first, and when you drain the oil out of the pan, most of the oil in the pump and pickup also drain out. Then when you fire up the engine, that "dry" (not really but it isn't "pre-charged") pump and pickup assembly have to refill, and that's the suction side of the pump which is slower to charge than the outlet side is. The pressure passages in the pump, relief passage(s), block, crank, heads are all still mostly full as they don't readily drain back, well unless you let it sit for a few months and they might but if we're doing an oil change we don't let them sit for months to drain do we?
if you have a good 0-100 digital gauge you'll see that there is a little bit of pressure right away, typically 1-5 psi, and in a few seconds it comes up to normal.
but here's my take on this, as usual when forums discuss anything oil, they get all technical and stuff, and the knowledge is based on what we have read on other websites. It starts a war a lot of times and generally I don't get involved. But I've been through this both with engine training and with engine lubricant training at a former job (training done by the manufacturer). What people don't often think about is if you leave your, tractor in this case, sit in the barn for a few weeks, everything drains back into the pan and it takes longer to build oil pressure after sitting than it does if you do a normal oil and filter change. But we don't talk about that, for one there's nothing you can do about it. Well I guess one could install an oil accumulator to precharge the system before cranking, but again I don't know if that really does much good since the manufacturer designs the engine specifically knowing that a low/no pressure situation is GOING to occur after an oil change and/or after sitting for lengths of time. Even on my race car, an accumulator is useful for peace of mind but it doesn't make bearings and rings and such last any longer than without them. It still goes to 0-5 psi during shut down and stays like that for about 5-7 seconds, starting at 7800 RPM and backing down to about 2000 there isn't much oil pressure. In decades of running it, it's never caused an issue that I can see.
I've driven broken tractors from the back side of the building (at the old job) to the shop with zero oil in them. Fill em up after a pan replacement and they run for a long time. At one point I was given a BX2200 that was a total loss, but engine ran fine. Couldn't sell it, nobody wanted it so I did some of my own testing. Engine ran for over 40 minutes with zero oil in it until it finally just got so hot that the pistons seized in the bores-it never started knocking or anything. Let it cool off and for giggles I fired it up and it ran another 10 minutes. Just gave up on it, shut it off in amazement and went to bed. Next morning I had a response to the marketplace ad that I had the tractor listed on, guy wanted it for parts so I let him come get it. As said I couldn't sell it but there wasn't anything saying I couldn't give it to someone else.
