If I'm quadrupling the recipe for a red velvet cake do I still add four times the baking soda and powder?
I know some disagree, but I always have learned that recipes can start breaking down if more than doubling or halving. Ratios can start changing and need adjusted, and then there is the cooking time components. If I have a recipe I am happy with, and I want to greatly increase it, I normally will instead make multiple instances of the base recipe. If I want to make a cake recipe times 4 or times 6 for a large event for instance, I would instead make 4 or 6 instances and build the larger cake from them rather than risk disaster making a single large cake that did not come out right. If I had a bread recipe I like, but wanted to use it for an event, I would not try to make a loaf 6 times as large, I would make 6 loafs, and so on.
Here is a discussion that gets into some of the issues of what can go wrong when trying to scale recipes and why for instance someone making a wedding cake does not make one giant cake, they make a bunch of smaller ones and build that cake. http://kitchenscience.sci-toys.com/scaling