according to the warn act, a layoff has to include 50 or more people in a given location and does not include part-time or contract employees. I'm sure they stay just under that limit so they don't have to publicize that the layoff is coming. not that it is the ethical thing to do, but they dodge the requirement.
So much what @TrcEhHk-1ewo said. Not only is having more smaller layoffs better for DST in avoiding bad press, it keeps everybody from knowing how many people have truly been laid off. Have you noticed that the official number and the actual number of folks we know were shown the door never matches?