I've never grafted, cell punch or any thing like that. I'm foundationless mostly and when I make the hive queen less there is always some fresh drawn comb that they usually build the cells on.
I believe the feed they get from hatch to capped is all important.
I am in total agreement with your 2nd statement, and that is the main reason why I do not like emergency queens. To get a larvae from horizontal to vertical, the bees thin down the royal jelly and float the larvae out to the face of the comb where they can then build the vertical queen cell. My personal belief is that this thinned out royal jelly does not have the same nutritional value as non-thinned out. It is also being fed at the most critical time in the queens development, the period where the larvae is either going to become a worker or a queen. I understand the ease of creating emergency queens for the beekeeper, but I would suggest at least doing some OTS cell cuts to reduce the need for floating the larvae.
I've raised several queens in nucs and have experimented with it quite a bit. Six frames of nurse bees on young brood will always build me a pretty good queen. Four frames loaded with bees is my minimum.
It is not just good, it is good enough

I don't want to open the can of worms as to how big a colony is needed to make quality queens. There are many that say it can be done in a nuc, a lot that say a double deep, and all variations in between. Is it 3 frames, 5 frames, 7-1/2 frames, I don't know. But I think we can all agree that more does not hurt.
When I graft, put about 5lbs of nurse bees in a nuc for cell starter, and then use a double deep hive for cell finishing.
If I'm making splits without grafting, I will take the strong hive and take the queen and 2 frames of brood in a nuc to another yard. Then do OTS cuts in the strong hive. Once the cells are capped, I'll then split the hive into nucs with capped cells. This way cells are always built by a strong full sized colony.
I've read on the forums that many hives supersede 3 times a year but mine never do. I get a year out of most, some considerably longer.
I think that is a sad statement of the quality of queens we are raising. Unfortunately too many people think that just because we can force bees to make a queen cell, they will make good ones. If you look at feral colonies, supercedure is no where near as prevalent as we make it in our hives. I often ask, if supercedure queens are just as good, why do hives bother with queen cells? Why don't they just up and swarm and let the old hive raise a supercedure queen?
Good luck