Efficient here likely means purely character count. Not this series but in Kenja no Mago enchanting is limited my character count depending by item. So i think it's not a stretch to apply this here. Though on reality you'll probably run into storage space vs processing power tradeoff just like...
Unless otherwise specified by the author, I will believe he's basically Haruhi. A reality warper but is unknown or only works on subconscious level. Either that or a real god has taken a real liking to him.
Any plans on adding custom height?
I know that there is a setting for custom width but i need custom height. For now i made a script for setting max-width and max-height.
https://gist.github.com/LordZero25/4ed77aab499bbeb85a632f8ded3493fd