In SWAT's very early days, before pagers, we submitted a roster listing personnel and all phone numbers where they'd be for the holidays so they could be reached in the event of a callup. Not surprisingly, callup notifications often took a long time. Pagers helped speed up the process somewhat, and the team pager streamlined things even more. As technology continues to advance, costly notification delays are no longer a factor in SWAT callups.
Whether or not your team is actually called out on holidays, you're always aware you can get called out at any time. While most in SWAT eventually get used to being on call, the possibility is always in the back of your mind.
SWAT callups on holidays are like lightning strikes in a thunderstorm - hitting all around you. And you know some team in your area is going to be called out. For some reason, we had a lot of Thanksgiving callups, but Christmas callups were rare. I guess we were lucky since nearly every Christmas some other team in our area would have to handle a SWAT callup. The luck of the draw, I guess.
But with the exception of Christmas day, callups, raids, and searches picked up dramatically in my area. Raids and searches were a daily thing, and barricade and hostage situations seemed to occur in clusters of two, three, or four in a row.
The reality is all of LE is busy during the holiday season - something all street cops know firsthand. More people out and about means more criminals and crime. More crime means more arrests and confrontations. Which in turn means more SWAT missions. The busier all of LE is, the busier SWAT is.