Okay, I admit it, I'm addicted to tracking my story's rankings on Amazon (and checking sales). I don't know why precisely, but I like to see when one of my stories drops below the 100k mark. That's an indicator of sales, but not an indicator of major sales (you have to drop down into the 10-20k range for decent sales and the 1-5k range for good sales, and the below 1k rank for sellng like hot cakes).
Honestly, however, the sales rankings on Amazon mean nothing to a writer. Not really. Those rankings, according to noted authority James D. MacDonald over on the Absolute Write forum, are for the readers to allow them to judge the popularity of a book they might be thinking about purchasing.
Personally, I'm beginning to think it's a mistake to put rankings up at all. It's definitely a mistake for a writer to obsess over them and fret about them.
I mean, if you walk into a brick and morter bookstore, you're not going to see books arrayed in some kind of artificial ranking system. You'll see bestsellers, new releases, and books laid out for special sales or holiday seasons, but you will never see a ranking number attached to those books or see them placed on the shelves in any specific order.
What the Amazon rankings do is tell a reader "Hey, this book is popular". The idea begins with the assumption that a reader cannot judge for themselves what book they're actually looking for. In essence, Amazon's ranking system assumes the reader is stupid in my opinion. The rankings, made by some arbitrarily mysterious algorithm, can even be "gamed" (and have been) by savvy or clever marketers. The rankings are not, as is commonly believed, based solely on sales alone (though they probably should be), but Amazon won't tell us what the rest is based on. A guess can be made that it's partially sales, partially searches, partially value, etc., etc., all of which factor into the algorthm that spits out an arbitrary number that the writers can obsess over the numbers and the readers can make entirely arbitrary decisions about the work without even sampling it.
The fact is, the only numbers that should matter to the writer are sales - and they shouldn't matter all that much. Stories either work or they don't. It is impossible to predict whether a story will sell or appeal to readers or not (believe me, some of the stuff I thought was my best work has so far flopped worse than a freshly-caught trout on a rock).
Amazon's rankings might be intended to attract readers, but I think readers should think for themselves. Only you know what you like. Amazon can make suggestions based on what you've purchased or searched for previously, but they can't tell the reader what they like any more than the writer can predict what the reader is going to like and buy.
Be your own person. Read what you want. Do not let Amazon or anyone else try to steer you in any particular direction as a reader.
As a writer, forget those rankings. They're not for you. Look at your sales instead, but don't obsess over them either. You've got better things to do.
Like writing your next piece.