Actually, why would a department really want to pay to have you go present the SAME thing at a bunch of different conferences? You've done the work once, you should get to follow it through once. This just sounds like they've cut people off from doing some nubbin of work and getting 5 trips around the country totaling weeks away from the program all on the program's dime. Heck, some conference rules prevent you doing that anyhow. Maybe I'm reading that differently than everyone else. Now, if you've done separate work, with separate abstracts and the possibility of separate article publications, then sure, go present each one of those at different meetings and the program should pay -- within reason. But IMO it's easier to say "we'll pay for 1/2/3 conferences per year, no more" than this publication thing -- it can take a year plus to get publications through sometimes. If their logic is simply to get more things actually published, well, that's their prerogative.
From my recollection, anyone who had something accepted for presentation could go to at least 1 major conference per year on the program's dime. I don't remember what the cap was in terms of how many conferences one could go to within a year on the program's money, but I think one existed -- I seem to recall someone at some point lining up quite a few and trying for some international conference(s) and eventually someone had to draw the line.