I've occasionally requested a song several times in one week. The main reason I've done this is because sometimes the song doesn't get played until after I've left my desk. Due to the delay in processing requests (which I understand is partly programmatic, but probably also due to other requests in the queue), I can sometimes request a song at 10 am my time, and it doesn't get played until after I go to lunch at noon. I've come back from lunch on occasion to find that I missed my song by 5 minutes.
I'll also sometimes request several songs by an artist over the course of a week, because I'm trying to get enoguh of a handle on them to decide whether to buy their stuff. For artists who only have one or two albums up on AM, this means requesting tracks from the same album, of course.
In this latter case, I tend to make requests partly by song length (figuring a 9-minute track is more likely to give me a feel for the band than a 3-minute track), and partly by song title (if the title "sounds interesting"). Not an exact science, I know!
(FWIW, I almost always requests songs I'm interested in hearing but don't actually know; most songs I
know I like I tend to buy the CDs of.)
I bring all this up not as a matter of objection - I'm happy to have AM around in practically any form, and understand why the moderators have taken the actions described earlier in this thread - but as another data point for how someone uses the request system. (In fact, there's a song on the playlist which was getting played seemingly every morning for a while which I simply could not stand, and I'm happy if it means we'll be hearing less of it!)
I actually rarely make requests, primarily because of the long delay before they get played. I don't often have a 3-hour block of time when I know I'll be around and listening to AM, either at work or at home (though once baseball season ends, I may have more such blocks of time at home!).