No it's not you, that really threw me off as well. I've worked on fairly large data mining software and we almost always talked about requests on a per second basis (sometimes requests per day if we were discussing aggregate projects and total output). Using requests per month would be...astronomical. Hell, one product was running 100M requests per day (though to be fair not every request was 1:1 bound to a corresponding database read or write op).

That brings me to my next observation: I don't want to demean the author, but 15 rps is really not extraordinary, so I'm wondering why these requests are so expensive. I assume there is a good reason they need to focus on "scaling" that many, I just can't figure out exactly what it is. They might be doing a lot of very inconsistent throughput with hard to predict peaks, I guess...