Thanks for the responses. (including the others i did not quote, and not directed at me. largely Talking about Slime.)
i thought as much when i saw the 30% reduction. It basically reads as, If you're on a tight schedule run, which means less time to gather currency. (for aura) Plates are the way to go.
While with slime, reduction is best. (in other words, Higher cost materials/Higher Value Materials per Summon-Mana Cost)
(Quality/Efficiency for slimes feedings.)
(Quality/Efficiency or Power/Cost for Aura)
thanks again for the info. (always a wonder how to find the right keyword for things.)
Edit:
Continuing with what some have said about slime.
While one can feed the slime to level it up.
What about using Drugs and other items on it. while pointlessly expensive. i know you can drop some of the consumables on it that increases its HP. (like memories)
Is it worth while alongside feeding, as a way to dispose of any items you dont need?(or want to use for that run.)