The inefficiencies of Christmas.
'Tis the season to be jolly - and to feign delight at disappointing Christmas presents.
The average British adult splurged around ￡550 ($667) on gifts in 2021, according to one survey.
Another Christmas inefficiency for retailers is the fact that it comes but once a year.
Gary Grant of The Entertainer, which sells toys, jokes that he would love it if festive sales were spread throughout the year rather than being crammed into the final quarter.
He is understaffed, he says, during the holiday season, when he expands his workforce by 50%, and then overstaffed the rest of the year.
Shipping companies, warehouse operators and sorting centers must also organise themselves to meet peak demand; that can mean unused capacity at quieter times of the year.
Data from Metapack, a logistics software company, suggest that in December the volume of posted parcels is more than double the level in September.
Over time, it does seem that consumers are spreading their spending a little more thinly across the year.
In 1986 25% of the year's spending on clothing was in November and December.
In 2019 the share was 22%.
Seasonality in retail spending, which includes restaurants, is also falling.
Seasonal employment as a share of the total between October and December has been decreasing since 1997, according to the Office for National Statistics.
A new study by Mr. Waldfogel found that since 2000 growth in the American economy has been associated with a smaller seasonal bump in December's retail sales.
While some dream of white Christmases, others may yearn for mandatory exchanges of cash, or even a mechanism to randomly allocate the celebrations evenly across months of the year.
Much would be lost if such a system were adopted, not least the joy that can accompany the exchange of carefully (if badly) chosen presents.
But creating a fresh batch of unintended consequences for economists to analyse might yield some happy returns.