I have a few professional cookbooks and many home cookbooks. Sometimes, I want to scale a large recipe down for home use, other times I want to double or quadruple a home recipe for a large crowd. Usually, I just multiply or divide all the quantities by the desired factor and hope for the best.
Are there general principles for scaling different kinds of recipes up or down? What kinds of recipes are not conducive to direct scaling?
This question is very broad, and deliberately so. I think it has the makings of an interesting thread.