Backed by the data
Go light on the leavening
This is the one change in the whole dish model we can
actually stand behind for spread. Less baking soda, less spread,
measured consistently across the corpus and the only relationship
that held up once we corrected for testing several outcomes at once.
What to do: don't add extra baking soda hoping
for puffier gingerbread men. If crisp edges and a held shape matter
more to you than lift, err light.
Good kitchen practice, unproven here
Chill the dough before rolling anyway
We tested chilling time against edge texture and it
did not clear, the same as every roll-versus-scoop comparison on this
page. Chilling still makes stiff dough easier to roll thin and cut
cleanly, which is a real reason to do it even without a measured
result behind the shape claim.
What to do: chill it if the dough is too soft to
cut cleanly. Don't expect the chill alone to fix a spread problem the
leavening caused.
Don't blame this
The butter probably isn't why it spread
Butter showed only a borderline, unproven hint on edge
texture and nothing that held up on spread at all. A cookie that
spread more than expected points at leavening before it points at
the butter.
What to do: if a batch spread on you, check the
baking soda measurement first.