Speaking personally from being on the receiving end of a bonus, and from a family business with a similar tradition to what Xrac has implemented, I think it's much more important to be transparent and stick to a set cadence. You're worrying about trying to squeeze out a few hours of production in a couple weeks when really an annual bonus is meant to reward consistent loyal help. Paying it in November vs December or January really doesn't make a difference, Xrac is just trying to be helpful to his employees who might want to take advantage of some sales. Annual also can be calendar year or fiscal year or some random month, so his employees have worked the 12 months since last bonus anyway.
I doubt his employees aren't thinking that they can take it easy in December.. they're probably thinking about it in July when they are dreaming of a beach vacation the following year.
You could also set some guidelines about how business performance affects end of year bonuses.. if it's profit sharing, then everyone can get behind trying to keep costs down, and selling more services..
Just food for thought.