Visually, Book Report stacks the blue on top of the red - the blue sales are "higher" in November than October because they're sitting on top of higher red sales. I actually made less in blue KU sales in November, which I usually see in any kind of promo, because people are more inclined to purchase outright when the price has been lowered.
Book Report doesn't break down earnings of sales except day-by-day, and I can't be bothered adding 60 of them up, but I know the box set shoots past the 3,000 page cap so I earn about $12 for a full-book "borrow." So, back of the envelope calculations:
October - $333.47
23 borrows = $276 in KU reads
6 sales at full royalty = $57.47
November - $439.99
18 borrows = $216 in KU reads
165 sales at reduced royalty = $223.99
So, yeah, an extra hundred bucks, which isn't pointless, but isn't exactly earth-shattering for an official Amazon promo. To be honest I don't know exactly what a "Kindle Deal" gets you except the book being put on one of those endlessly long lists. I assume the algorithm becomes kinder to a book Amazon is promoting but that's just conjecture.
On the other hand, of course, it's free; I could probably get better results with several of the promo sites (and obviously with a Bookbub) but maybe not the same net profit. I suppose there's also the argument that extra copies in readers' hands has the longer-term benefit of more reviews and more readers potentially interested in your other books (though I'm not convinced many readers of this box set ever actually migrate to my other books).
