I think first and foremost that it would end up requiring a lot of extra effort from wharvey to chase down delinquents more often and to keep track of who needs to receives gifts when. wharvey also noted the lack of gifts being shipped, so having more time to shop and ship would probably be better for most people. Of course participants can always request gifts by particular dates, but having one official date for the whole thing I think helps simplify it.

I also think (and hope) that most, if not all, participants participate in this in the spirit of holiday gift exchange and that it's not exclusive or religiously motivated. If we started doing observed holidays, then we would end up with so many deadlines for different people unless you draw a line somewhere. For example, the next holiday I tend to observe after Thanksgiving is the lunar new year, with the next one being Feb 16 2018. If you want to make it nondenominational then you could request that this be changed to the "Flyertalk Holiday Gift Exchange" and set a (mostly) nondenominational deadline of the new (Gregorian) year. (hopefully not too OMNI)