Hi there. Thanks for the suggestion.
I am going to leave the recipes as is for a few QOL and QOL-adjacent reasons including the ability to handcraft recipes that depend on zircon when you only have stone, and the fact that for a certain amount of zircon, the stone you need is guaranteed.
I do also think solving this on a sushi belt has a clear enough solution to not be blocking, but also allows for some interesting complex solutions if someone wishes to optimize differently.