For myself, when using the wide base JZsBZs cell cups, like you show in your photo, I only accept cells where the entire plastic base is full of royal jelly, or very nearly so, when they are sealed. A very few of the cells in this photo have slightly less than full plastic cell bases -->
Most batches of cells I raise are way more than I need, each round. So I use the very best looking cells first, and discard any cells that don't contain a large surplus of royal jelly once they're old enough to plant. I often have a few cells that probably would have produced some fairly nice queens -- but they weren't selected first, so they get discarded.
Cells that look like these are usually those that are selected and planted, first -->
The following cell bars were culled/discarded in their entirety, they just weren't grown well enough to meet my standards -->
I hadn't thought of actually priming with large amounts of royal jelly -- I had sometimes sacrificed a cell to rob its royal jelly to mix with a little water and use that mixture to prime a bar of new cell grafts with a tiny drop in each.
Now this has got me thinking to try doing a double graft, by aborting a bar of larvae once the cells are nearly full of royal jelly, but before they're sealed, then removing those larvae and re-grafting with new larvae grafted into the full bed of royal jelly. I know that "double grafting" is mentioned in many of the literature about queen rearing, and is often tried by the authors of those books, but it is usually discarded as a method to produce superior queens. I'm thinking that, even if something were tried before, that it couldn't hurt to try it for myself -- maybe I might discover a nuance that could imbue a positive benefit, not before seen.
I'm definitely going to need to assemble a lot more four compartment, 3-frame mating nucs.