Netflix, famously, had a public contents to try to improve the recommendation system, with very little success. [1] That system was a demonstrably good system, that maximizes preference, but only if you rate a bunch of content. I'm not aware if it's still in use.
But, I've rated many hundreds of shows/movies, and the rating is very accurate, for me. Very biased and scaled, but completely predictable/reliable.
In my case, the rating can be corrected with Netflix 7 being my 0, and Netflix 10 being my 10, mostly linear. For a Netflix show, 8 is my 0, since those are biased a bit more.
But, I've rated many hundreds of shows/movies, and the rating is very accurate, for me. Very biased and scaled, but completely predictable/reliable.
In my case, the rating can be corrected with Netflix 7 being my 0, and Netflix 10 being my 10, mostly linear. For a Netflix show, 8 is my 0, since those are biased a bit more.
[1] https://en.wikipedia.org/wiki/Netflix_Prize