To give a bit more context, hourly employees are laid off and draw unemployment during these planned shutdowns. It sounds super weird, but it's been happening for over 50 years, so everyone knows what they are getting into. The same hourly employees are hired back again at the end of the shutdown.

I'm not exactly sure what happens for downtime more than a couple shifts, but I'm sure the union remembers it in the next negotiations.

Lots of people who work construction draw all winter.

Where? Here in the D.C. area, construction does not stop because of weather. The exception would be extreme weather such as hurricanes, lightning and rain if the building was not closed in. It actually seems that construction increases in the winter, I guess because of fresh budgets. There is a joke that they only start breaking ground when it is the coldest time of the year.

This happens in DC too, although perhaps to a lesser extent due to your mild climate. Some construction continues through the winter, and most carpenters and laborers are happy to work instead of draw, but nobody is framing in the snow. It's true that excavation is easier when the ground isn't muddy, so "breaking ground" in the winter could make sense. You can't pour concrete when it's freezing, though, so if the timing is wrong the rain could mess up the excavation before you get a chance to place your forms.

It's pretty typical for auto companies to shut down for ~2 weeks over the summer and in December. Ford does the same thing. It gives the companies two big windows for planned maintenance on their machinery which helps the plants run more consistently the rest of the year.

Volvo's summer factory shutdown in Sweden is even longer.