The reason the driver side galley create problem is that it is fed off the right side, as noted. But that in and of itself wouldn't matter except it creates an added demand on the right side that the right side can't keep up with. I fully agree with 'cutting off' the left side....at least as far as feeding it through the long and winding path of the #1 main bearing saddle goes.
If #4 is starved because of the left side galley, it's not because of velocity but because the 'drain' imposed by the left galley prevents the right galley from maintaining pressure. When the right side's pressure sags, it might well starve #4. But the sag is from lack of pressure/volume, not because of velocity.
This says it well "Pressure would fix it, because pressure is resistance to flow - if there's more pressure it's because more volume is available."
You can't keep the pressure up if the volume sags. When you can't move enough oil, the first thing that drops is pressure. Why can't you move enough oil? Could be the pump is too small, the passages are too small, or the 'leak' is too large. But velocity? Nope.