So, in the 5 years that I've used Spotify, I've never been happy with how the music I listen to is used for my "daily" playlists. Music I listen to a year ago will flood all of my daily playlists. If I find a new band, listen to only them for a month straight, I won't see that new band on my "for you".
Similarly, blacklisting songs/artists does not work. If playlist A is based on a band I don't like, and I blacklist every song by that artist, that playlist won't even update for a week. When playlist A does update & remove the blacklisted band, playlist C will now be based on the blacklisted band.
Here is a specific example. I like Gorillaz & Blur. Both of these bands are lead by Damon Albarn. Damon has another band called "The Good, The Bad, & The Queen.". I don't care for this group & that's ok. But in the last 2 years I've had to blacklist every song by them on 3 different albums multiple times. Because if playlist A is based on Damon Albarn, & I've blacklisted too many songs by him for that playlist to be possible, it'll turn playlist C into another Albarn playlist with every song I've blacklisted. These blacklists are only good for a year I guess because every year I have to do this all over again.
Again, if I blacklist 87/92 songs by Good, Bad, Queen, I will have to blacklist the remaining 12 songs because they will appear on my premade playlists.
tl;dr daily playlists update too infrequently, pull their metrics from too old of data, and do not share blacklist information between daily playlists.