It's pretty common knowledge that Also Boughts (ABs) are a very important source of discoverability, and ABs kicking in quickly can really knock a launch out of the park.

Having a pretty middling new launch right now (~#3500 rank) but it's made over 100 sales and 8,000 page reads since it came out on Thursday. Nothing special compared to most vets I know, but I'm wondering... shouldn't 100 sales be enough to trigger ABs? Then I wondered how ABs even work in the first place, I realize it's a big mystery for me.

Let's discuss AB experiences and theories. Here are some questions I'd love to have answered.

1. Should an author ever message KDP about missing ABs, or assume that if they're not up, they're not meant to be up?
2. Do KU reads trigger ABs or do only sales count? I imagine KU readers read a lot more books in a genre because they have access to free books, Amazon is bound to have lots of buyer habit information to tailor the best recommendations, which then gets them more money.
3. Are the number of reviews a possible factor?
4. Are there any AB 'hacks' (not black hat, just tips and tricks) that can help boost a book?
5. Does being in a multi-author bundle skew your ABs by linking them with the other authors in the bundle? Seems to me like this could have a negative effect, if you're in a bundle of 20 authors and only 2 of them are bestsellers, the other 18 have poor rank.
6. How do readers on different devices encounter Also Boughts? What makes ABs so important and powerful, especially compared to Also Viewed and Sponsored Products Related To This Book which don't seem to give as much of a boost?