I worked at an ecom unicorn that did this and had been doing so for about a decade. I think it saved them quite a bit of money by giving extra time off to ops

I worked at an ecom unicorn that did this and had been doing so for about a decade. I think it saved them quite a bit of money by giving extra time off to ops in exchange for their extra work during the holidays. Code freezes (in my experience) don't actually reduce the number of bugs or incidents. I think in all probability they increase the number of incidents and cost money because of the warm up period. But they do shift the timing when incidents occur, and that can be nice if your customers are sensitive to holiday sales. It's also nice to your employees. Paying your SREs a bit more for their tour of duty to the customers and employees is worth it.