I really think Spotify should take a page for Native Instruments Traktor in how to organize a library; create and edit playlists. My 1st attempt at a playlist I just dumped a bunch of tracks I felt suitable for it. Turned out to be 8+ hours of music. So I decided to break it all up into volumes, different playlists. Well...It's rather annoying that you cannot move tracks to another playlist but instead have to make copies and transfer. So that means you have to deal with all the duplicates.
Why on earth I cannot just transfer tracks to a new playlist without making duplicates is...I dunno. Also the lack of dual window panels to transfer tracks from search to playlist, from one playlist to another makes building playlists a pain.
If your on computer you can actually use drag drop and or ctrl X + ctrl V.
Highlight the song you want to move by clicking on it, press ctrl X to cut it then go to the new destination and do ctrl V to paste it, because you did ctrl X and not ctrl C, it will remove it from the original playlist, you can highlight multiple by holding down ctrl as you click the songs.