Yep, I know what you're talking about, but spotify weights songs it thinks you'll like higher than other songs, and with big playlists it really is a noticeable problem. There are services that shuffle the order of your playlist, so then in spotify you play it with spotifys shuffle turned off, and yes there are "patterns" that I notice (one song I had in their twice, I think like a single version and album version, was right next to itself), but at least I actually hear songs I haven't heard in a long time, and I don't get the same ones regularly