All copiers have a special sensor that can tell how desperate you are to make the copy(ies). If don't need the copy for several hours, everything works fine. If you've ducked out of a meeting to make 10 copies of something that was just sprung on you, you are guaranteed the mother-of-all-paper-jams. And the only person in the office who knows how to unjam the damn thing has just left for lunch...or maternity leave...depends on how important the copy is.