They do warn, but the wholesellers decide whether to pass on the communication or not. UPS store and the Customer Service Centers will tell you. The risk of not keeping TnT (Time In Transit) is always there. There are frequent surges, depending on where you are... conventions, rodeos, tech shows, college students ordering books at large unis in small towns, bad weather, fires (like the ones we have every summer in many states in the west), and general accidents such as train derailments and hub fires. There's something going on every month to delay your package somewhere. It's just easier to hide if it just a few hubs. The unions jack up a lot too. They determine how much you get paid (yes, they do). There is a negotiated pool of regular salary, then the union decides who gets what portion. The unloaders, sorters, and loaders in the hubs are crapped on majorly. Drivers get a much better wage, but still not amazing. The haulers (big rigs, trailer runners (to and from the rail yard)) get the lion's share. Teamsters considers these lower class employees. The big truckers are well respected. If the pay was better, they'd get more people to show up and we wouldn't have this problem. I worked at UPS for many years. They hire 100% of people who apply and can show up every day. The training lasts weeks too. It's really not easy to take an ordinary person and get them into shape, learn to use the equipment well enough, and get them to learn the sort (sorting is nearly always by memory, zip -> binX). Holliday temps are a joke. They don't know how to use the equipment and they don't know ANY of the sorts. So they become okay temporary muscle, usually not lasting the entire peak season (Thanksgiving to Christmas). During peak, always add a day or two to your TnT and be suprised when it arrives early. And by the way, package priority is: Early AM > Next Day Air > 2nd day > air freight > 3rd / ground.