Scaling Rennet Coagulated Cheese Making Recipes - Starter Culture Amount?

[Cheese Head]

This topic had a short discussion in this Intro Thread and has been I think partially addressed in other Threads, but as it will get buried in that Board and not all our members read the Intro posts, this specific topic is kicked off here.

Question, for lineally scaling rennet coagulated cheese making recipes larger or smaller (normally by amount of milk), how do you scale the amount of starter culture and why?