My wife and I shared an Amazon account with two Kindles for years. The account was in my email address so I would receive an email from Amazon regularly with recommendations for additional books to read based on what I was reading. Since there were two of us with different interests reading as one, the recommendations were a mess. I prefer non-fiction and science fiction while my wife reads a wider range of genres. Amazon's computer must have thought we were weird and confused.
A few months ago, we split the account and now she has her own and I have my own. She is getting recommendations that are homing in on her interests, but mine are still a mess. I'm wondering how long it will take to Amazon to zoom in on my interests.