The direct answer
84 recipes
We could not fit a measured effect
Not for chew, not for spread, not for anything else we
checked. Resting time never cleared as a lever in our data.
That is a real result, not a shrug. We split the corpus by
how long each recipe rests, none, short or long, and compared the
groups on every outcome we track. None of the usual reasons people
chill dough showed up as something we could measure.
What to do: if your recipe calls for a rest, follow
it. It was formulated as part of a system. If it does not, you are not
missing anything we can prove.
We looked, and found nothing
84 recipes
It makes cookies chewier
We could not detect it. Resting time varies enormously across these
recipes and it never lined up with how chewy the result was.
This is the claim cooks make most often in our reviews, so
we want to be careful about what we are saying. Not detected is not the
same as disproved: an effect smaller than the spread of these recipes
would look exactly like this to us. But if chilling were the reliable
chewiness lever it is described as, we would expect to see it, and we do
not.
What to do: if chew is what you are after, brown
sugar is the lever with evidence behind it.
A trend, not a lever
84 recipes
It stops them spreading
Partly. Recipes that rest longer do come out
thinner than average, but resting never became a measured lever,
so the effect is smaller and less consistent than the advice implies.
This is the honest middle that neither side of the
argument occupies. King Arthur is not wrong that the direction exists.
The pages calling it optional are not wrong that it will not rescue a
formula. Chilling nudges. It does not fix.
What to do: if yours are spreading badly, weigh the
flour and look at the butter before you reach for the fridge.