UPS packages are always moving through the sorting facilities and are traveling on the planes and on the trucks so that the UPS packages get to your location on time.
UPS sorts packages all week long including Saturdays and Sundays as well including all holidays but UPS will only deliver packages on non Holidays and on all days including Saturday except for Sunday.
UPS doesn't deliver packages to your door on Sunday or major Holidays and will deliver the package the next working day when it isn't a holiday.