My boss thought we could save time by pre-mixing all dry ingredients for the month, and now we have a mountain of flour in the break room. | Bakers - The Community Guide
Actually, pre-mixing dry ingredients that far ahead is a real baking no-go (sorry boss). Flour soaks up smells from everything, and any baking powder in that mix would start to lose its power after a few days, let alone a whole month. That’s probably a big part of the cardboard taste right there. You just can’t beat mixing those things fresh right before you bake.