[jhawk28]

Two main mistakes that people make: 1. "scoop and dump" approach to flour. Flour should be spooned into the measuring cup so its not packed in. 2. over-baking cookies due to cooking too long or oven that is too hot or not hot enough.

[Dilettante_]

The flour should not be packed? I've always done it like that, it seemed so obvious that that would give a less random result that having it loose. I guess I'll weigh it and check against the markings on my measuring cup next time.

[jtc331]

Brown sugar should be packed; flour must not be — you’ll get substantially more mass per volume than the recipes assume.

[ip26]

Some pack, some sift and scoop. You have to know what the recipe wants. Weigh is in my opinion superior, it just wasn’t widely accessible before cheap digital scales.

[ksenzee]

In my four decades of baking, I have never seen a recipe that calls for packing flour. It is always sifted, spooned and leveled, or weighed.

[shermantanktop]

Weighing is the only weigh.

[bluGill]

four is alway sifted - to get the mouse droppings out. In our modern world nobody has mouse droppings in flour but tradition is still strong. Weighing doesn't care but if you are scouping as much air as possible is what the recipe assumes.

[tzs]

Or measure flour by weight instead of volume.

[karlshea]

Flour should be weighed.