It's not entirely uncommon, even companies like Volkswagen have 3 weeks of summer vacation. Strictly speaking, some people still work there for maintenance, etc. that can't be done while making cars, but the majority is on vacation.

I know a handful of companies with a week of mandatory Christmas vacation as well (but there's typically not too many working days between Christmas and New Years' either way).

In England, I had summer jobs in factories when I was a teenager, since they needed extra hands to help with cleaning / maintenance during the annual shutdown.

I don't know if this work would have been offered to staff who turned it down, or if they preferred to have their staff on holiday at the same time.