I could be wrong but after reading about pushrod oiling until my head was going to explode, I'm of the opinion that too much oil up top is not a good thing. If there's excess oil just sitting there in the head trough you end up starving the bottom end where the oil is needed the most. Wives tale? I dunno but oil surely does not drain back into the crank case a fast as it gets pushed through the galleries or orifices.
I thought about that dual oiling scenario myself but concluded it's not a good idea. I'd say either one or the other but not both since pushrod oiling (generally) requires blocking the feed to the heads because the oil is now coming through the pushrods. Besides, you'd need rocker arms that pushrod oil (basically T&D = $$$). But eithr way, the main drawback to that idea is that you'd have pretty low oil pressure if you're feeding oil to the top through two separate circuits instead of just one. The less leaks the better, right?
Just as an example, I used to shift my old W2 340 at 7,200 with the standard shaft oiling system and a HV oil pump with no observable issues. I didn't know as much then as I know now but I definitey would have known if things were getting burned up due to a lack of oil or what have you and for sure they weren't. General wear from use/heat cycling etc. is a different story.