Cisco - end of year shutdown. Love it. Sorry, did not read the title correctly, Cisco shutdown requires you to take some of your PTO days off during the shutdown period. But, what I like is everyone in your team except who volunteered is off and you don’t have to come back to a pile of work waiting for you 😀
Small company I used to do consulting for shut down last 12 days of the year since most staff would take off anyway and clients would be offline.
Large company I consulted for would have shutdown periods in summer but would take volunteers for reliability engineering coverage. Those volunteers would get their choice of a bonus or additional time off.