The reason the simplified diagram is 'good' is that the remainder of the oiling system - rockers, cam bearings etc. have nothing to do with whether or not the oil is willing to take a turn to go the #4 main. That's the whole point of the question....to discuss if the 'oil will keep on truckin past #4' bit has merit or not.
You could even argue that since #4 feeds the rockers, it presents a greater loss than the mains which don't feed rockers. Therefore, the oil in the galley is more likely to seek the low pressure area and the #4 would be an 'oil hog' as compared to #3, for instance. It probably pulls more oil off the galley, not less. The problem is that it serves three masters - the mains/cam bearings/rockers - and there's not enough to go around.
So Duane says engines that run a front feed also run a rear feed. YR says they never do. You two gotta work that out lol. I'll tell you I've seen it both ways but more often it is only one. I think guys do one because it is easier, not because they've decided it's better. For the belted oil pump engine, feeding in the front is way more tidy. Plus, it was an easy mod for Chrysler to make to the block, so they did it.
If you have a single pump and you split the output into two line, then feed those two lines into the same manifold, it'll work fine....that is assuming you take some time to balance the hoses, etc. The pressure in the galley is not the same as it shows on the gauge? I fully agree....that's precisely why the double feed is good - it helps achieve the goal of balanced feed across the engine.