Tricky Ingredients

Not everything scales linearly. Salt and spices are subjective and usually need less than proportional scaling, so the smart move is to scale them lightly, then taste and adjust. Baking soda and powder are even fussier: they react with the batter and with pan size, so tripling a cake can throw off the rise unless you adjust.

Cooking times also don't scale linearly. A larger roast takes longer per pound because heat has to reach a thicker center. A doubled pot of soup behaves differently: it is mostly liquid that stirs and circulates, so the heat spreads quickly and the simmer time barely changes even when the volume does.