After 37signals posted how they sped up their test suite considerably by using cookies directly instead of signing a user in for every test, I wanted to do the same. Why spend more time than necessary on testing, am I right?
Sometimes you have to get ahead of things. Rate limits suck but are there for a reason, waiting until the API you are calling raises a rate limit error is bad, really bad. This is how you get ahead and prevent the external API from raising rate limit errors.