I've been noticing that when I listen to any of the "daily mixes" (which don't update daily) and also the artist radio and suggested songs based off of my listening history, there are a LOT of repeat songs. I listen to mostly punk and ska so my genre pool should be pretty limited which in this case is a good thing.
I was never able to find any concrete evidence so I had to create my own. I wanted to see how often Spotify duplicates their recommendations. I started with Rancid Radio which is a pretty household punk name. I loaded their 50 song radio playlist. It had 32 unique artists in that playlist. So I then went to all of those artists and added their 50 song "radio" playlists to mine. It left me with 118 unique artists and 1400 songs. After doing some work in Excel, I found it had 1013 duplicate songs. That left it with 388 TOTAL UNIQUE SONGS. Over the span of basically 33 Spotify curated playlists. Now, I'm not saying there shouldn't be some duplicate songs, but this is where it gets ridiculous. Here are some of the duplicates.
100 Proof by 88 Fingers Louie 23 times
Cool Kids by Screenching Weasel 26 times
Linoleum by Nofx 19 times
Nightlife by Off With Their Heads 20 times
On a Turntable by The Interrupters 22 times
Silence is Golden but Duct Tape is Silver by Against All Authority 23 times
Skate or Die by Teenage Bottlerocket 24 times
26 times? That means that one song was on 79% of the artist playlists! Sure, play the artist on 79% o them but maybe choose new songs! Most of the artists had 1 or 2 songs and I think at most an artist would have maybe 5 songs. Each of these artists have a log of anywhere from 50-150 songs and yet you're only giving us at most 5. This is just straight up ridiculous.
https://youtu.be/f0mEagUzG3o
https://youtube.com/shorts/HkHafrbMpSE?feature=share