You also have to ensure that the machine is learning what is actually necessary. I recently bought a new Chevy Silverado and the amount of SPAM I now get about Chevy Silverado's being on sale is insane. I just bought one... why the hell would anyone think I'm in the market for another? Stupid. Just plain stupid. The machine learned how to be a total moroff ("Moroff" is worse than "Moron" because it's more off than on :D).
How do you like the Silverado? I bought a 2018 Chevy Colorado for the trip to/from Rhode Island. I like the truck, handles well, and did well with the trailer we towed to Rhode Island.