AL said:

I'm hardly an expert, but I would say a mistake would be to not make sure
the paying customer understands that humidity related shrinkage gaps are to
be expected. Maybe a mockup showing what it will look like in the winter is
in order.

Or take the opportunity to sell them a furnace humidifier as well.
It has worked wonders for our house and furniture, and an added
benefit is that you are less susceptible to colds.
FWIW,

Greg G.