Holy cow, I wrote a book!
There are a few times a year when
a large fraction of employees are out on vacation at the same time,
such as a single work day
wedged between a holiday and a weekend (as happened this year
on July 5).
The most extreme case of this
is the week between the Christmas holiday and New Year's Day,
where the offices are practically empty.
On these days of low demand,
many services are scaled back and some choose to close entirely
so that they can do inventory, perform routine maintenance,
or upgrade equipment.
One of the most visible service reductions is in food service.
Smaller locations (such as snack bars) are closed,
and the kitchens which remain open offer a reduced menu.
But just because most people are on vacation doesn't mean
that nobody is watching.
Here's a menu from one kitchen
that was posted almost exactly one year ago: