If charges occur, the following may help to explain why. Your library probably maintains a list of libraries that do not charge, and it will contact these libraries first. As a last resort, it will contact libraries that have charges. Photocopies are subject to standard ILL rates as our on-campus students make and pay for their own photocopying. Though communication between libraries happens electronically, the actual delivery of materials is handled through the U.S. Postal Service.
Books are generally shipped book rate and photocopies mailed first class.
Schedules and workloads will also vary from library to library. Other factors that might affect turnaround time are the accuracy of your citations, the scarcity of the items you want, or even the time of year. Please note that most libraries will refuse to send any packages during the Christmas mailing season. Please treat all materials carefully. Some libraries may pass on to patron charges for lost or damaged items.