This might be a function of low usage time, the shifts were definitely more pronounced in the beginning, now when I listen to new stuff it only introduces the changes in the appropriate mixes (i.e my mix 1-3 is various hiphop (very well segregated into different styles i must add), 4,5 is indie/rock etc) and the amount is a function of how much of said new stuff i listen. On occasion i will use votes and the dislikes especially affect playlists quickly.
I know the youtube behaviour you refer to and it honestly really makes me hate watching youtube, some days I will have a bad mood and start spamming not interested for a few rows and my feed is good again.
But with YTM it seems to be really nice, whereas with spotify, as OP, I found it quite stale.