I'm a huge fan of the Discover Weekly playlist. Most of the time it is so good that you can get in touch at least with 2-3 new songs. Sometimes I also have a lucky day where nearly every single song matches my taste but was unknown to me. This is a really great example of what algorithms can do. But it also proves that more is not better. If I imagine the playlist would be refreshed every day as planned or a list of 100 songs instead of 30- I wouldn't use it anymore. It simply would be to much to progress each week. The current amount is perfect to start a working week and I do so since that playlist started.