Retailers put a lot of work into their forecasts for seasonal lines each year, but the aim is a clean sell through.
It makes more sense to order x amount (which is still an increase on last year) which has a good variety until 1/2 days before Christmas and sell through your last item on Christmas Eve, than order too much and end up having to reduce everything left with any sort of Christmas graphic on Boxing Day.
It’s a balancing act that is a lot harder than it looks. Forecasting can only go so far- you can use every LY sales figure possible to predict, but it’s ultimately just a prediction.
Much harder when it’s fresh items though rather than ambient. At least with chocolate even if it doesn’t all sell, you know you have a few months to sell it. Turkeys etc are much more expensive and after Christmas, as you know, the demand just disappears. Again, that’s why turkeys will sell out early on Christmas Eve and you’ll hear stories of Christmas being ruined. Ordering too much stock is a liability.